* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download P - Coastal Bend College
Survey
Document related concepts
Transcript
MATH 1314 College Algebra Unit 3 Polynomial Functions Section: 5.1 Polynomial Functions • This section studies the Polynomial Function. Your Goal - learn to identify the function components that lead to its characteristic graph behavior. • Polynomial function: refer to page 327. Leading coefficient degree of 𝑓(𝑥) is the highest power 𝑛. 𝑓 𝑥 = 𝒂𝒏 𝑥 𝒏 + 𝑎𝑛−1 𝑥 𝑛−1 + ⋯ + 𝑎1 𝑥 1 + 𝒂𝟎 Leading term: determines the end behavior of graph & number of complex zeros Constant term (y-intercept) any combination of variable terms and constant term can exist. all coefficients are real numbers exponents are non-negative integers variable cannot be in a denominator graphs are smooth and continuous Polynomial Functions • Practice: According to the description of a polynomial function, which of the following are considered polynomial functions? P O P O O ? 𝑓 𝑥 ? 𝑓 𝑥 ? 𝑓 𝑥 ? 𝑓 𝑥 ? 𝑓 𝑥 1 = 5 Why? Follows Polynomial form. 𝑥 → 𝑥2 = 𝑥 2 + 3 𝑥 − 4 Why not? Exponents must be = 1 3 − 𝑥 5 1 + 𝑥 4 = 𝑥 2 +2𝑥−15 𝑥 2 −4 +7 nonnegative integers. Why? Follows Polynomial form. Can’t have a variable Why not? in denominator. = 𝑥 −2 + 4𝑥 + 1 Why not? Exponents must be nonnegative integers. Polynomial Functions • Exercise: Graph. Determine end behavior rules for 𝑓 𝑥 = 𝑎𝑥 𝑛 . 1 5 𝑌1 = 𝑥 2 𝑌1 = 3𝑥 4 𝑌1 = 𝑥 6 up Conclusion: if degree is even and 𝑎 > 0, both ends go _______. P 1 5 𝑌1 = − 𝑥 2 𝑌1 = −3𝑥 4 𝑌1 = −𝑥 6 down Conclusion: if degree is even and 𝑎 < 0, both ends go _______. P Polynomial Functions • Exercise: Graph. Determine end behavior rules for 𝑓(𝑥) = 𝑎𝑥 𝑛 . 𝑌1 = 3𝑥 1 4 𝑌1 = 𝑥 3 𝑌1 = 𝑥 5 down Conclusion: if degree is odd and 𝑎 > 0, left end goes ________ P up right end goes ________. 𝑌1 = −3𝑥 𝑌1 = 1 3 − 𝑥 4 𝑌1 = −𝑥 5 up Conclusion: if degree is odd and 𝑎 < 0, left end goes _______ P right end goes _______. down Polynomial Functions • Theorems and Definitions Real Zeros: A real number 𝑥 = 𝑟 that makes 𝑓 𝑥 P called a real zero of 𝑓(𝑥). This means that: = 0 is 𝑥 = 𝑟 is an x-intercept of 𝑓(𝑥) and a solution to 𝑓(𝑥) = 0. 𝑥 − 𝑟 is a factor of 𝑓(𝑥) . Multiplicity: If 𝑥 − 𝑟 occurs in 𝑓(𝑥) an even or odd number of times, then 𝑥 = 𝑟 is a zero having even or odd multiplicity. even multiplicity: graph touches x-axis at 𝑥 = 𝑟. odd multiplicity: graph crosses x-axis at 𝑥 = 𝑟. Turning Points: If a polynomial function has degree 𝑛, then its graph has at most 𝑛 − 1 turning points, and vice-versa. End Behavior: ends of the graph of polynomial 𝑓(𝑥) resembles the graph of its leading term 𝑎𝑛 𝑥 𝑛 . P P P Polynomial Functions For the polynomial function below, find its real zeros and multiplicity. 𝑓(𝑥) = (𝑥 + 5)2 (𝑥 − 2) factors (𝑥 − 𝑐) are: (𝑥 + 5), (𝑥 + 5), (𝑥 − 2) zeros 𝑥 = 𝑐 are: 𝑥 + 5 = 0, 𝑥 + 5 = 0, 𝑥 − 2 = 0 𝑥 = −5, 𝑥 = −5 multiplicity 2 𝑥=2 multiplicity 1 **Find the polynomial function having the given real zeros and multiplicity. degree: 3 zeros: −4 multiplicity 1, 3 multiplicity 2 zeros 𝑥 = 𝑐 are: 𝑥 = −4, 𝑥 = 3, 𝑥 = 3 factors (𝑥 − 𝑐) are: (𝑥 + 4), (𝑥 − 3), (𝑥 − 3) 𝑓(𝑥) = (𝑥 + 4)(𝑥 − 3)(𝑥 − 3) = (𝑥 + 4)(𝑥 − 3)2 = 𝑥 3 − 2𝑥 2 − 15𝑥 + 36 P Polynomial Functions Your turn. Practice. Find the polynomial function 𝑓(𝑥) whose degree is 4 and zeros are: −1 with multiplicity 2 Occurs twice 7 with multiplicity 2 Occurs twice zeros 𝑥 = 𝑐 factors (𝑥 − 𝑐) −1, −1, 7, 7 (𝑥 + 1),(𝑥 + 1) ,(𝑥 − 7),(𝑥 − 7) P P So 𝑓(𝑥) = (𝑥 + 1)(𝑥 + 1)(𝑥 − 7)(𝑥 − 7) = (𝑥 + 1)2 (𝑥 − 7)2 = 𝑥 4 − 12𝑥 3 + 22𝑥 2 + 84𝑥 + 49 P Polynomial Functions Practice. If 𝑓 𝑥 = 𝑥 4 + 2𝑥 3 + 𝑥 2 , find the following: 0, −1 a) real zeros: _______________ P Factor, then solve each factor for 𝑥. 𝑥 4 + 2𝑥 3 + 𝑥 2 = 0 𝑥 2 (𝑥 𝑥 2 + 2𝑥 + 1) 1 =0 𝑥2 𝑥 + 1 𝑥 + 1 = 0 𝑥2 = 0 , 𝑥+1=0,𝑥+1=0 𝑥 = −1 , 𝑥 = −1 𝑥 =0,𝑥 =0 Polynomial Functions Practice ….continued. If 𝑓 𝑥 = 𝑥 4 + 2𝑥 3 + 𝑥 2 , find the following: b) Graph crosses or touches x-axis at: 𝟎 largest, largest zero _________ touches occurs twice multiplicity −𝟏 smallest, occurs twice multiplicity P touches P smallest zero _________ Degree 𝑛 − 1 c) Maximum number of turning points on the graph of the function: _____ 3 **Remember Turning Points Theorem P Polynomial Functions Practice. If 𝑓 𝑥 = 5(𝑥 2 − 3)(𝑥 + 4)2 , find the following: 3, − 3, −4 a) real zeros: _______________ P Solve each factor for 𝑥. 𝑥2 − 3 = 0 𝑥+4=0 𝑥+4=0 𝑥 = −4 𝑥 = −4 𝑥2 = 3 𝑥=± 3 3 −4 − 3 ∞ = 3, − 3 −∞ 0 𝟑 largest, 1 multiplicity of largest zero is: ____ occurs once − 𝟑 middle, 1 multiplicity of middle zero is: ____ occurs once −𝟒 smallest, 2 multiplicity of smallest zero is: ____ occurs twice P P P Polynomial Functions Practice ….continued. If 𝑓 𝑥 = 5(𝑥 2 − 3)(𝑥 + 4)2 , find the following: b) Graph crosses or touches x-axis at: 𝟑 largest, crosses occurs once largest zero _________ − 𝟑 middle, crosses occurs once middle zero _________ −𝟒 middle, touches occurs twice smallest zero _________ P P P multiplicity multiplicity multiplicity c) Maximum number of turning points Degree 𝑛 − 1 3 on the graph of the function: _____ P d) Power function that graph resembles 5𝑥 P for large values of 𝑥 : _____ 4 Practice and Complete HW 5.1 MATH 1314 College Algebra Unit 3 Real Zeros of Polynomial Functions Section: 5.2 Real Zeros Section 5.1 asked: Find real zeros of polynomial 𝑓(𝑥). Helpful: 𝑓(𝑥) was already factored or 𝑓(𝑥) was easily factored. 𝑓 𝑥 = 𝑥 + 1 2 (𝑥 − 3) 𝑓 𝑥 = 𝑥 3 − 6𝑥 2 + 9𝑥 Section 5.2 explains how to find real zeros in: polynomial 𝑓(𝑥) that are not already factored or polynomial 𝑓(𝑥) that are not easily factored. Real Zeros • Some Theorems that can be used to find real zeros and factors of polynomial functions Remainder Theorem(p347): If polynomial 𝑓(𝑥) is divided by linear factor 𝑥 − 𝑐, then 𝑓(𝑐) = remainder. Factor Theorem(p348): If 𝑓 𝑐 = 0, then 𝑥 − 𝑐 is a linear factor of 𝑓(𝑥). If 𝑥 − 𝑐 is a linear factor of 𝑓(𝑥), then 𝑓 𝑐 = 0. Number of Real Zeros Theorem(p349): A polynomial cannot have more real zeros than its degree. Intermediate Value Theorem(p355): For a continuous function 𝑓(𝑥), if 𝑎 < 𝑏 and if 𝑓(𝑎) and 𝑓(𝑏) have opposite signs, then 𝑓(𝑥) has at least one zero between 𝑥 = 𝑎 and 𝑥 = 𝑏. Real Zeros • Practice: How to factor polynomial functions using the previous theorems. Factor 𝑓 𝑥 = 2𝑥 3 − 11𝑥 2 + 10𝑥 + 8: Is 𝑥 + 1 a factor of 𝑓(𝑥)? If 𝑥 + 1 is a factor, then 𝑥 = −1 is a zero of 𝑓(𝑥). Using Remainder Theorem, since 𝑓 −1 = −15 ≠ 0, you know that 𝑥 + 1 is not a factor of 𝑓 𝑥 . Is 𝑥 − 4 a factor of 𝑓(𝑥)? If 𝑥 − 4 is a factor, then 𝑥 = 4 is a zero of 𝑓(𝑥). Using Remainder Theorem, since 𝑓 4 = 0, you know that 𝑥 − 4 is a factor of 𝑓 𝑥 . Real Zeros Synthetic Division will use a divisor 𝑐 to find zeros, remainder, and factors of polynomial function 𝑓(𝑥). Practice: Coefficient writing Polynomial function 𝑓 𝑥 = 𝑥 3 − 7𝑥 2 + 4𝑥 + 1 has real coefficients: 1 −7 4 1 Polynomial function 𝑓 𝑥 = 𝑥 4 + 5𝑥 2 − 3 𝑓 𝑥 = 𝑥 4 + 0𝑥 3 + 5𝑥 2 + 0𝑥 − 3 has real coefficients: 1 0 5 0 −3 *Insert a zero coefficient for any missing terms. Real Zeros Practice: Use Synthetic Division to find remainder and quotient if 𝑓 𝑥 = 𝑥 3 + 3𝑥 2 − 6𝑥 − 8 is divided by 𝑥 + 4. divisor 𝑥+4=0 𝑥 = −4 𝑐 −4 multiply multiply 1coefficients 3 add − 6 add of 𝑓(𝑥) 1 −4 −1 4 −2 coefficients in last row make Quotient and Remainder: 1 −1 −2 0 Quotient is 𝑥 2 − 𝑥 − 2 Remainder is 0 −8 8 0 add Real Zeros Since 𝑥 + 4 produced a zero remainder, 𝑥 = −4 is a zero. To find remaining zeros in quotient 𝑥 2 − 𝑥 − 2: Factor or use Quadratic Formula. −(𝑏) ± (𝑏)2 −4 𝑎 𝑐 𝑥= 2(𝑎) −(−1) ± (−1)2 −4 1 −2 𝑥= 2(1) 𝑥= 1± 9 1±3 1 3 = = = ± 2 2 2 2 Zeros of 𝑓(𝑥): Factors of 𝑓 𝑥 = 𝑥= 1 2 1 2 3 + 2 3 − 2 =2 = −1 P (𝑥 + 4)(𝑥 − 2)(𝑥 + 1) P −4, an d 2, an d −1 an d Real Zeros Practice: Does 𝑓 𝑥 = 2𝑥 3 + 5𝑥 2 − 3𝑥 + 8 have a real zero between 𝑥 = −6 and 𝑥 = −1? Use Intermediate Value Theorem: Find 𝑓(−6) and 𝑓(−1). 𝑓 −6 = −226 𝑓 −1 = 14 P P P 𝑓(−6) and 𝑓(−1) have opposite signs. YES. Practice and Complete HW 5.2 MATH 1314 College Algebra Unit 3 Complex Zeros of Polynomial Functions Section: 5.3 Real Zeros Section 5.1 asked: Find real zeros of polynomial 𝑓(𝑥). factored or was ____________. easily factored 𝑓(𝑥) was either _______ Section 5.2 asked: Find real zeros of polynomial 𝑓(𝑥). factored or was not easily factored 𝑓(𝑥) was either not __________ _______________. To find real zeros of 𝑓(𝑥), you learned to use: • theorems, such as Remainder _________ Theorem and Factor _____ Theorem Synthetic Division • and a form of division called _______________. Section 5.3: Find Complex _______ zeros of polynomial 𝑓(𝑥). Complex zeros include non-real or imaginary ________ zeros additional theorems will be used. Complex Zeros Complex numbers: Standard Form 𝑎 + 𝑏𝑖 𝑎, 𝑏 are real numbers real part imaginary part To prepare for this section, review: Operations on complex numbers(p120-124) Definition of imaginary number: 𝑖 = −1 2 𝑖 2 = −1 𝑖 2 = −1 ? OO ? ? Is −4 = 2 = −2 ? 2 ? 2 Only if −2 Only if 2 = −4= −4 −4 = 4 ∙ −1 = 4 ∙ −1 −4 = 2𝑖 Complex solutions of Quadratic Equations(p124-126) Complex Zeros • Some Theorems you will use in this section: Fundamental Theorem of Algebra: (textbook p360) • Every polynomial function of degree 𝑛 ≥ 1, has at least one complex zero. Conjugate Pairs Theorem: (textbook p360) • Let 𝑓(𝑥) be a polynomial function whose coefficients are real. If 𝑟 = 𝑎 + 𝑏𝑖 is a zero of f, then the complex conjugate 𝑟 = 𝑎 − 𝑏𝑖 is also. *(The Quadratic Formula is the basis for this.) Corollary: (textbook p361) • A polynomial function 𝑓(𝑥) of odd degree with real coefficients has at least one real zero. *(This guarantees something important that we can use.) Complex Zeros Identifying Conjugate Pairs: the complex conjugate of 3 + 4𝑖 is: 3 − 4𝑖 the complex conjugate of −1 − 𝑖 is: −1 + 𝑖 the complex conjugate of 2𝑖 is: −2𝑖 Remember, non-real or imaginary numbers are the result of an even root of a negative number. Example: −16 = (16)(−1) = 16 ∙ −1 = 4𝑖 Complex Zeros Practice: If 3𝑖 is a zero of 𝑓 𝑥 = 𝑥 3 + 2𝑥 2 + 9𝑥 + 18, find the remaining zeros of 𝑓 𝑥 . 3 complex zeros exist. Why? degree 3 If 3𝑖 is a zero, then ____ −3𝑖 is also. Why? Conjugate Pairs Theorem Third zero must be real. Why? Corollary(p361): Odd degree Use Synthetic/Long Division to find third zero 3𝑖 1 1 −3𝑖 1 1 2 9 18 2 −18 3𝑖 6𝑖 −9 +9(−1) +9𝑖 0 2 + 3𝑖 6𝑖 2 + 3𝑖 6𝑖 −3𝑖 −6𝑖 2 0 𝑥 + 2 = 0 Solve for third zero. 𝑥 = −2 Remaining zeros: −3𝑖, −2 P Complex Zeros Practice: If 3𝑖 is a zero of 𝑓 𝑥 = 𝑥 3 + 2𝑥 2 + 9𝑥 + 18, find the remaining zeros of 𝑓 𝑥 . Or use TABLE/GRAPH on TI-83/84, if possible. Remaining zeros are : −3𝑖, −2 Complex Zeros Exercise: Find the complex zeros of 𝑓(𝑥), then use the zeros to factor 𝑓(𝑥). 𝑓 𝑥 = 2𝑥 3 − 12𝑥 2 + 13𝑥 − 15 Degree is odd, one real zero exists. Find with Rational Zeros Theorem(p349) or with TI-83 GRAPH/TABLE if possible. …continued Complex Zeros Exercise: Find the complex zeros of 𝑓(𝑥), then use the zeros to factor 𝑓(𝑥). 𝑓 𝑥 = 2𝑥 3 − 12𝑥 2 + 13𝑥 − 15 First real zero: 𝑥 = 5 *Since TI-83 GRAPH/TABLE doesn’t show 2 more real zeros, they may be nonreal. Use Synthetic Division to divide 𝑓(𝑥) by 𝑥 = 5 to find quotient. 2 − 12 13 − 15 5 10 −10 15 0 2 3 −2 Quotient is 2𝑥 2 − 2𝑥 + 3. Two complex zeros remain. …continued Complex Zeros Use Quadratic Formula to find remaining 2 zeros in quotient 2𝑥 2 − 2𝑥 + 3. −(𝑏) ± (𝑏)2 −4 𝑎 𝑐 𝑥= 2(𝑎) −(−2) ± (−2)2 −4 2 3 𝑥= 2(2) 1 𝑖 5 2 2𝑖 5 2 ± 2𝑖 5 2 ± −4 ∙ 5 2 ± −20 = ± = ± = = = 2 2 4 4 4 4 4 Zeros of 𝑓 𝑥 : 5, 1 𝑖 5 + , 2 2 1 𝑖 5 − 2 2 1 𝑖 5 1 𝑖 5 )(𝑥 − + ) Factors of 𝑓 𝑥 = (𝑥 − 5)(𝑥 − − 2 2 2 2 Practice and Complete HW 5.3 MATH 1314 College Algebra Unit 3 Properties & Graphs of Rational Functions Section(s): 5.4. – 5.5 Rational Functions A Rational function is a ratio of Polynomial Functions: 𝑅 𝑥 = 𝑝(𝑥) 𝑞(𝑥) , where 𝑞 𝑥 ≠ 0. Practice factoring (p50) Domain: all real numbers 𝑥, where 𝑞 𝑥 ≠ 0. Asymptote: a boundary line in which the graph of 𝑅(𝑥) may possibly intersect or never intersect. Types of Asymptotes(p367-368) Vertical Asymptotes, Horizontal Asymptotes, Oblique Asymptotes (Which one can never be intersected by the graph of 𝑅(𝑥)?) Rational Functions Graph of 𝑅 𝑥 = 𝑓 𝑥 = 𝑝(𝑥) 𝑞(𝑥) 𝑥−1 (𝑥−3)(𝑥+2) 𝑥 + 2 ≠ 0, so 𝑥 ≠ −2 𝑥 − 3 ≠ 0, so 𝑥 ≠ 3 𝑥−1 𝑥 2 −𝑥−6 Remember, if 𝑓(𝑥) looked like this : 𝑓 𝑥 = then what Algebraic skill is needed to help determine the restricted domain values of 𝑓(𝑥)? Factoring P Rational Functions To find Domain 𝑓(𝑥) must be factored completely. find restricted values from denominator. Practice: Domain 𝑓 𝑥 = 2 (𝑥 + 1)(𝑥 − 5) 5𝑥 + 10 𝑓 𝑥 = 2 𝑥 −𝑥−6 5(𝑥 + 2) = (𝑥 − 3)(𝑥 + 2) Find restricted values 𝑥 + 1 ≠ 0, 𝑥 − 5 ≠ 0 𝑓 𝑥 is factored factor 𝑓 𝑥 𝑥 ≠ −1, 𝑥 ≠ 5 Domain of 𝑓(𝑥). P Find restricted values 𝑥 − 3 ≠ 0, 𝑥 + 2 ≠ 0 𝑥 ≠ 3, 𝑥 ≠ −2 Domain of 𝑓(𝑥). P Rational Functions To find Vertical Asymptote(VA) after Domain 𝑓(𝑥) must be factored and reduced. find zeros of denominator. Practice: Vertical Asymptotes. 𝑓 𝑥 = 2 (𝑥 + 1)(𝑥 − 5) 𝑓 𝑥 is factored, does not reduce. 5𝑥 + 10 factor 𝑓 𝑥 𝑓 𝑥 = 2 and reduce. 𝑥 −𝑥−6 5(𝑥 + 2) 5 = = (𝑥 − 3)(𝑥 + 2) 𝑥−3 Find zeros of denominator. 𝑥 + 1 = 0, 𝑥 − 5 = 0 P 𝑥 = −1, 𝑥 = 5 Vertical Asymptotes Find zeros of denominator. 𝑥−3=0 𝑥=3 Vertical Asymptote P Important: Normally, a VA should have occurred when 𝑥 + 2 = 0 or 𝑥 = −2, but when the factor 𝑥 + 2 reduces out of the function, the VA is lost at 𝑥 = −2 5 and instead, a hole occurs in the graph of 𝑓 𝑥 = 𝑥−3 at 𝑥 = −2. Rational Functions To find Horizontal Asymptote(HA) if degree of numerator < degree of denominator, then 𝑦 = 0 is equation of HA, or if degree of numerator = degree of denominator, then 𝑦 = 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑜𝑓 𝑝(𝑥) 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑜𝑓 𝑞(𝑥) is equation of HA. Practice: Horizontal Asymptotes 𝑓 𝑥 = 4𝑥 numerator degree is 1 𝑥 2 − 9 denominator degree is 2. 3𝑥 2 −𝑥 𝑓 𝑥 = 2 1𝑥 + 4𝑥 − 5 numerator degree is 2 denominator degree is 2. P 𝑦=0 Horizontal Asymptote P 3 3 𝑦= =3 1 1 Horizontal Asymptote Rational Functions To find Oblique Asymptote(OA) if degree of numerator > degree of denominator, then 𝑦 = 𝑞𝑢𝑜𝑡𝑖𝑒𝑛𝑡 of 𝑝(𝑥) 𝑞(𝑥) is equation of OA. Synthetic Division used to find 𝑞𝑢𝑜𝑡𝑖𝑒𝑛𝑡 of Practice: Oblique Asymptote 𝑝(𝑥) 𝑞(𝑥) . 2𝑥 2 − 5 numerator degree is 2 Oblique Asymptote 𝑓 𝑥 = 𝑝(𝑥) denominator degree is 1. 𝑦 = quotient of . 𝑥−4 𝑞(𝑥) 2𝑥 2 + 0𝑥 − 5 = 𝑥−4 4 2 0 −5 8 32 2 8 27 OA at 𝑦 = 2𝑥 + 8 P ∞ Rational Functions Practice: Domain: 𝑥 ≠ 4 Range: 𝑦 ≠ −3 ∞ −∞ VA: 𝑥 = 4 HA: 𝑦 = −3 OA: 𝑛𝑜𝑛𝑒 Intercepts: 𝑥 = 0 𝑦=0 −∞ Rational Functions Practice: Find the following for 𝑓(𝑥). 2𝑥 2 + 3𝑥 − 5 (2𝑥 + 5)(𝑥 − 1) 2𝑥 + 5 𝑓 𝑥 = 2 = = 𝑥 + 3𝑥 − 4 (𝑥 + 4)(𝑥 − 1) 𝑥+4 P Domain: 𝑥 ≠ −4 , 𝑥 ≠ 1 Factor 𝑓(𝑥), find restricted values in denominator. Vertical Asymptote: P 𝑥 = −4 Must reduce 𝑓(𝑥) if possible, then find zeros of denominator. Horizontal Asymptote: Degrees are equal, use 𝑦 = Oblique Asymptote: 2 1 P 𝑦= =2 𝑛𝑢𝑚𝑒𝑟𝑎𝑡𝑜𝑟 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑑𝑒𝑛𝑜𝑚𝑖𝑛𝑎𝑡𝑜𝑟 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 No Oblique Asymptote . P Degrees are equal, so 𝑓(𝑥) cannot have Oblique Asymptote. Complete and Practice HW 5.4-5.5 Rational Functions Practice: Find the following for 𝑓(𝑥). 4𝑥 4𝑥 𝑓 𝑥 = 2 = 𝑥 − 11𝑥 + 18 (𝑥 − 9)(𝑥 − 2) 𝑥 − 9 ≠ 0, 𝑥 − 2 ≠ 0 P 𝑥 ≠ 9, 𝑥 ≠ 2 Domain: 𝑥 ≠ 9 , 𝑥 ≠ 2 Factor 𝑓(𝑥), find restricted values in denominator. Vertical Asymptote equation(s): 𝑥 − 9 = 0, 𝑥 − 2 = 0 𝑥 = 9, 𝑥 = 2 𝑥 = 9, 𝑥 = 2 P Must reduce 𝑓(𝑥) if possible, then find zeros of denominator. P Horizontal Asymptote equation: 𝑦 = 0 Numerator degree 1 < denominator degree 2. P Oblique Asymptote equation: No Oblique Asymptote 𝑓(𝑥) cannot have Oblique and Horizontal Asymptote. Rational Functions Practice: Find the following for 𝑓(𝑥). 2𝑥 2 + 3𝑥 − 5 (2𝑥 + 5)(𝑥 − 1) 2𝑥 + 5 𝑓 𝑥 = 2 = = 𝑥 + 3𝑥 − 4 (𝑥 + 4)(𝑥 − 1) 𝑥+4 P Domain: 𝑥 ≠ −4 , 𝑥 ≠ 1 Factor 𝑓(𝑥), find restricted values in denominator. Vertical Asymptote: P 𝑥 = −4 Must reduce 𝑓(𝑥) if possible, then find zeros of denominator. Horizontal Asymptote: Degrees are equal, use 𝑦 = Oblique Asymptote: 2 1 P 𝑦= =2 𝑛𝑢𝑚𝑒𝑟𝑎𝑡𝑜𝑟 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑑𝑒𝑛𝑜𝑚𝑖𝑛𝑎𝑡𝑜𝑟 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 No Oblique Asymptote . P Degrees are equal, so 𝑓(𝑥) cannot have Oblique Asymptote. Rational Functions Practice: Find the following for 𝑓(𝑥). 5𝑥 2 + 7𝑥 − 6 (5𝑥 − 3)(𝑥 + 2) 𝑓 𝑥 = = 5𝑥 − 3 = 𝑥+2 𝑥+2 Domain: 𝑥 ≠ −2 P Factor 𝑓(𝑥), find restricted values of denominator. P Vertical Asymptote equations(s): None Must reduce 𝑓(𝑥) if possible, then find zeros of denominator. 𝑓(𝑥) reduces, no zeros from denominator. P Horizontal Asymptote equation: None Numerator degree 2 > denominator degree 1. 𝑓(𝑥) has Oblique but no Horizontal Asymptote. Oblique Asymptote: 𝑦 = 5𝑥 − 3 P Use Long Division or reduced 𝑓(𝑥) to get quotient Complete and Practice HW 5.4-5.5 MATH 1314 College Algebra Unit 3 Polynomial & Rational Inequalities Section: 5.6 Polynomial & Rational Inequalities • This section focuses on learning how to find Rational the solutions to Polynomial _________ & _______ Inequalities. • Solving inequalities follows the same solving equations procedure as _______________, with one exception: reverse the inequality when multiplying or always __________________ negative constant dividing by a _______________. −2𝑥 + 1 < 9 Example: Solve for x. −2 −5 + 1 < 9 −2 −1 + 1 < 9 11 < 9 3<9 O ( O −∞ )( −4 P −1 −2𝑥 < 8 ) ∞ 0 −1 −2 −2 < −4 𝑥> P Polynomial & Rational Inequalities • When you solve a polynomial inequality, like the one below, you are trying to find coordinates on the x-values that lead to __________ _______ 𝑦<0 polynomial’s graph that have ______. 𝑥2 − 𝑥 − 2 < 0 • There are two ways to do this: Algebraically Graphically P The graph method is at a disadvantage if exact x-values are required. Polynomial & Rational Inequalities • When solving Polynomial & Rational Inequalities, always rewrite inequality in Standard Form: 𝑓 𝑥 < 0 , 𝑓(𝑥) > 0, 𝑓(𝑥) ≤ 0, 𝑓(𝑥) ≥ 0 What each inequality means relative to its graph: 𝑓 𝑥 < 0 means “for which intervals is graph below 𝑥-axis without touching it?” 𝑓(𝑥) > 0 means “for which intervals is graph above 𝑥-axis without touching it?” 𝑓(𝑥) ≤ 0 means “for which intervals is graph below 𝑥-axis and touches it?” 𝑓(𝑥) ≥ 0 means “for which intervals is graph above 𝑥-axis and touches it?” To solve Polynomial or Rational Inequalities(Standard Form): 1) Polynomial: Find real zeros to form intervals on number line. Rational: Find real zeros of Numerator & Denominator* to form intervals on number line. If < or >, intervals use ( only. If ≤ or ≥, intervals use [ only at numerator zeros, use ( everywhere else. 2) 3) Test a number in each interval using inequality in Standard Form. Choose interval that satisfies inequality in Standard Form. Poly. & Rational Inequalities Practice: Reading inequalities & graphs. ∞ 𝑦>0 𝑦=3 𝑦 ≅ 4.8? ≅ 4.75? 𝑦=2 𝑦 = 0.5 𝑦<0 Poly. & Rational Inequalities Practice: Reading graph intervals. Find 𝑓 𝑥 < 0. Use graph of 𝑓(𝑥) below. P Answer: (−∞, −3) ( −∞ P) 𝑓 𝑥 <0 ∞ Poly. & Rational Inequalities Practice: Reading graph intervals. Find 𝑓 𝑥 > 0. Use graph of 𝑓(𝑥) below. P Answer: (−3,0) ∪ (0, ∞) 𝑓 𝑥 >0 −∞ ( P)( P ) ∞ Poly. & Rational Inequalities Practice: Use the graph of 𝑓(𝑥) to solve the inequality. P P Inequality to use parentheses Answer:indicates (−4,0) ∪ (6, ∞) only. Inequality use ∪ brackets Answer:indicates −∞, to −4 [0,6)only at x-intercepts. 𝑓 𝑥 ≥0 ( −∞ 𝑓 𝑥 ≥0 )( )[ )( .. 𝑓 𝑥 <0 .. ) ∞ 𝑓 𝑥 <0 Poly. & Rational Inequalities Practice: Solve 𝑓(𝑥) < 0, where 𝑓 𝑥 = 𝑥(𝑥 − 5)2 1) Rewrite in Standard Form. Find zeros. 𝑓(𝑥) < 0 r r Interval I Interval II Interval III 𝑥(𝑥 − 5)2 < 0 −∞ 𝑥 = 0, 𝑥 − 5 = 0, 𝑥 − 5 = 0 −1 1 6 0 5 zeros are 𝑥 = 0, 𝑥 = 5 2) Test intervals using Standard Form. 𝑥(𝑥 − 5)2 < 0 (−1)(−1 − 5)2 < 0 Interval I : Test 𝑥 = −1 −36 < 0 ( Interval II : Test 𝑥 = 1 Interval III : Test 𝑥 = 6 3) Solution: (−∞, 0) )( )( (1)(1 − 5)2 < 0 16 < 0 r (6)(6 − 5)2 < 0 6<0r ) ∞ Poly. & Rational Inequalities Practice: Solve 𝑥 𝑥−3 ≥ 1. 1) Rewrite in Standard Form. Find zeros. 𝑥 (𝑥 − 3) − ≥0 𝑥−3 𝑥−3 𝑥 𝑥−3 ≥ 𝑥−3 𝑥−3 Solve denominator 𝑥 − 3 = 0 𝑥=3 −∞ ( or [ at 𝑥 = 3? ( 2) Test intervals using Standard Form. Interval I : Test 𝑥 = 2 Interval II : Test 𝑥 = 4 3) Solution: 3, ∞ 3 ≥0 𝑥−3 r Interval I )3( 2 3 𝑥−3 Interval II ) ∞ 4 ≥0 3 ≥0 2 −3 3 ≥0 4 −3 −3 ≥ 0 r 3≥0 End - Unit 3 Complete assignments before Ch5 Exam Due Date