Chapter 8 - Polynomials and Factoring - 8-5 Factoring X(squared) + bx + c - Practice and Problem-Solving Exercises - Page 503: 31

(r-4)(r+1)

Given the polynomial $r^{2}$ - 3r - 4 *** We break of the middle term into two factors that add to give -3 and multiply to give -4. The two numbers are -4 and +1. $r^{2}$ - 4r +1r - 4 We take the GCD of the first two and the GDC of the last two terms. r(r-4) +1(r-4) We take (r-4) and factor it out which gives us. (r-4)(r+1)