McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
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Exercise 13 Page 217

Think of the process as multiplying two binomials in reverse.

Prime

Practice makes perfect
To factor a trinomial with a leading coefficient of one, think of the process as multiplying two binomials in reverse. Let's start by taking a look at the constant term. x^2-11x+15 In this case, we have 15. This is a positive number, so for the product of the constant terms in the factors to be positive, these constants must have the same sign (both positive or both negative.)
Factor Constants Product of Constants
1 and 15 15
- 1 and - 15 15
3 and 5 15
- 3 and - 5 15

Next, let's consider the coefficient of the linear term. x^2-11x+15 For this term, we need the sum of the factors that produced the constant term to equal the coefficient of the linear term, - 11.

Factor Constants Product of Constants and Variables Sum of Products
1 and 15 1x and 15x 16x
- 1 and - 15 - 1x and - 15x - 16x
3 and 5 3x and 5x 8x
- 3 and - 5 - 3x and - 5x - 8x

We did not find a factor constants whose product is 15 and also cause the sum of the products of x and the factor constants to equal - 11x. Thus, the polynomial is not factorable.