1. 8-5 FACTORING TRINOMIALS
Please work on the following problems on your notes
(start before the bell rings):
Warm up:
#1: Multiply: (x – 8)(x + 8)
#3: y2 + 4x2y + 5
a) Name polynomial (by terms)
b) Name polynomial (by degree)
#2: Factor
3x3 - 12x2 + 2x - 8

2. 8-5 Factoring Trinomials
ANSWERS
#1: Multiply: (x – 8)(x + 8)
x2 + 8x – 8x – 64
x2 – 64
#3: y2 + 4x2y + 5
a) Name polynomial (by terms)
Trinomial
b) Name polynomial (by degree)
Cubic
#2: Factor
3x3 - 12x2 + 2x - 8 x -4
3x2
3x3
-12x2 2x -8 2
(3x2 + 2)(x - 4)

3. Remember…
(x+2)(x+5) We used box method. Today, we are going to work BACKWARDS!  New method…. X-BOX!! x 5
Notice: 5•2 = 10
5 + 2 = 7 x x2 5x 2 2x 10

4. Example 1: Factor x2 + 14x + 45 x 9 x x2 9x 5 5x 45 x2 + 9x + 5x + 45

5. X-BOX METHOD G C F 1st•3rd First Term From “x” G C F From “x”
Last Term
2nd
2 # that MULTIPLY to top
and ADD to bottom

6. Example 2: Factor x2 – 2x – 35 x -7 x x2 -7x 5 5x -35-2 5 5x
-35
(x – 7)(x + 5)

7. Example 3: Factor
-12 12
1 12 + - 6

8. TOO  Factor

9. Homework
Delta Math Ch 8 Pt 2 (Week B) Due next Mon 2/4 8am

10. Helpful X hints. + + + + - - + - - -
+ big
- small
- big
+ small + -

11. Example 4: Factor x2 – 16xy + 48y2
x2 – 12xy – 4xy + 48y2 x
-12y 48 48
1 48 x x2
-12xy - 12 - 4
2 24
-16
3 16
-4xy
-4y
48y2
4 12
(x – 12y)(x – 4y)

12. TOO  Factor A rectangular skateboard park has an area of
x2 + 15x What are the possible dimensions of the park?