Chapter 11 - Rational Expressions and Functions - 11-2 Multiplying and Dividing Rational Expressions - Practice and Problem-Solving Exercises - Page 676: 67

$ \frac{(t-r)(t+2r)}{(t+r)(t-2r)}$

Given : $\frac{t^{2}-r^{2}}{t^{2}-tr-2r^{2}} \times \frac{t^{2}+3tr+2r^{2}}{t^{2}+2tr+r^{2}}$ $= \frac{(t-r)(t+r)}{(t+r)(t-2r)} \frac{(t+r)(t+2r)}{(t+r)(t+r)}$ $= \frac{(t-r)(t+2r)}{(t+r)(t-2r)}$ (After dividing out the common factors (t+r) and (t+r))