Download Chapter 5-12

Gautier/Tang
Algebra I: Ch. 5 Part 4
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Chapter 5-12
Zero-Product Property: If ab = 0, then a = 0 or b = 0
Examples:
1. Solve (x + 2)(x – 5) = 0
x+2=0
x = -2
x–5=0
- Set both factors equal to zero.
x=5
- Solve for x.
Solution set: (-2, 5) - Answer
2. Solve 3n(n – 8)(2n + 1) = 0
3n = 0
n–8=0
n=0
n=8
2n + 1 = 0
n = -1/2
- Set all factors equal to zero.
- Solve for x.
Solution = 0, 8, -1/2
3. Solve 2x 2 + 5x = 12
2x 2 + 5x – 12 = 0
(2x – 3)(x + 4)
2x – 3 = 0
3
x=
2
- Put the equation in standard form (descending powers)
- Factor (3rd kind of trinomial)
x+4=0
- Set both factors to zero.
x = 4
- Solve for x.
3

Solution set:  , 4  - Answer
2

*** HINT: Review all types of factoring to help you solve these more quickly
1
Gautier/Tang
Algebra I: Ch. 5 Part 4
Practice Problems
Directions- Solve
1. (y + 5)(y – 7) = 0
2. ( n + 1)(n + 9) = 0
4. 2x(x – 20) = 0
5. (2u + 7)(3u – 1) = 0
6. m 2 - 36 = 16m
7. 25m 2 - 16 = 0
8. 3x 2 + x = 2
9. x 2 = 20x – 100
10. (2t – 3)(3t – 2)= 0
11. y 2 = 16y
2
3. (x – 4)(x + 8) = 0
12. 6n 2 + n = 2