Chapter 6 - Section 6.2 - Factoring Trinomials of the Form x2+bx+c - Vocabulary and Readiness Check - Page 428: 7

$x^{2}$ - 7x + 12 = (x - 4)(x - 3) Answer is - 3

$x^{2}$ - 7x + 12 = (x - 4)(x - 3) We need factors of 12 whose sum is -7. But, one factor is already given $\rightarrow$ (-4). Thus the other factor is $\frac{12}{-4}$ = -3. All parameters are satisified since - 4 - 3 = - 7, and, (-4)(-3) = 12. Thus answer is is -3.