Chapter 7 - Rational Functions - 7.3 Multiplying and Dividing Rational Expressions - 7.3 Exercises - Page 580: 18

$= \frac{(t-4)(t-3)}{(t+2)(t-5)} $

$\frac{t^{2}-16}{t^{2}+9t+14} \times \frac{t^{2}+4t-21}{t^{2}-t-20}$ $= \frac{(t-4)(t+4)}{(t+7)(t+2)} \times \frac{(t+7)(t-3)}{(t+4)(t-5)}$ $= \frac{(t-4)(t+4)(t+7)(t-3)}{(t+7)(t+2)(t+4)(t-5)} $ $= \frac{(t-4)(t+7)(t-3)}{(t+7)(t+2)(t-5)} $ $= \frac{(t-4)(t-3)}{(t+2)(t-5)} $