Download Section 1.5

Week 2
1)
Warm Up
Write an equation:
m=2
03.25.13
( - 4, 7 ) , ( 2, 19 ).
y = mx + b
19 = 2(2) + b
19 = 4 + b
15 = b
y = 2x + 15
Re 1
x2 + 25x - 54
( x - 2 )( x + 27 )
Section
10.5 Day 3
Rule 1
Ex 1
I will solve quadratic equations by
factoring.
Set each bubble to zero and solve.
( x-5)( x+4) =0
x-5=0
x=5
x+4=0
x = -4
Ex 2
( x+6)( x-8) =0
x+6=0
x-8=0
x=8
x = -6
x = -6, 8
x2 - 8x + 6x - 48
x2 - 2x - 48
Don’t
Write
Rule
Ex 3
Sometimes I can solve a quadratic equation by
factoring instead of the quadratic formula.
Ex 3
Don’t
Write
Ex 4
x2 + 3x + 2 = 0
( x + 2 )( x + 1 ) = 0
x+1=0
x+2=0
x = -1
x = -2
x = -1 , -2
Check 1:
x2 - 11x – 80 = 0
( x + 5 )( x - 16 ) = 0
x+5=0
x - 16 = 0
x = -5
x = 16
x = -5 , 16
Rule 2
Equations must be solved for 0 before I can factor.
Ex 5
x2 + 9x + 16 = -4
x2 + 9x + 20 = 0
( x + 5 )( x + 4 ) = 0
x+5=0
x+4=0
x = -5
x = -4
x = -5 , -4
Ex 6
x2 - 5x – 20 = 0
(x
Rule 3
Answer
)( x
)=0
If I can’t Factor I have to use the
quadratic formula.
Review
If I cant factor a polynomial I use the
_____ ______.
Check 2:
x2 + 15x + 50 = -6
Assignment
Handout – Section 10.5 Day 3
a2 = 4a + 21
Ex 7
a2 – 4a - 21 = 0
( x - 7 )( x + 3 ) = 0
x-7=0
x+3=0
x =7
x = -3
x = -3 , 7