## Algebra 1

$r^{2}$ + 10 rs + 9 rs + $90s^{2}$ Find the GCD of the first two and the GDC of the last two terms. r(r + 10s) +9s(r + 10s) We take (r + 10s) and factor it out which gives us. (r + 10s)(r + 9s)