## Introductory Algebra for College Students (7th Edition)

(7x$^2$-1)(x+y)
7x$^2$(x+y) and -(x+y) both have the common factor of (x+y). When you take out this factor you are left with 7x$^2$ from the first term and -1 from the first term. The resulting factorization is written as (7x$^2$-1)(x+y)