# 4.6 Reasoning About Factoring Polynomials ```4.6 Reasoning About Factoring Polynomials
You can use the following checklist to decide how to factor an algebraic expression:
Divide out all the common factors first.
If the expression has two terms, check for a difference of squares: a － b = (a + b)(a － b)
2
2
If the expression has three terms and is in the form x2 + bx + c, then factor the sum and product.
ie: m + n = b and (m)(n) = c If the expression has three terms and is in the form ax2 + bx + c, then factor criss&shy;cross method.
If the expression has four or more terms, factor by grouping. 1
Factoring Strategies
Factoring is the process where a polynomial expression is written as a product of other algebraic expressions.
2
Practice: Factor completely
a) x2 &shy; 6x &shy; 27 c) &shy;18x4 + 32x2
b) x3 + 5x2 &shy; 14x d) 16x2 &shy; 88x + 121 e) x5y + x2y3 &shy; x3y3 &shy; y5 f) (x &shy; 1)2 &shy; (y + 7)2 3
A solid has volume defined by V = 4x3 &shy;12x2y + 9xy2.
Identify the type of solid.
4
2.
Determine a possible set of dimensions for each.
a)
b)
5
Homework:
pg. 236 #6 &shy; 13 and Workbook pages 6
7
8
9
10
11
12
13
14
15
16
```