Cách làm cho bạn:
a) $\frac{5x + 10}{4x - 8}$.$\frac{4 – 2x}{x + 2}$ = $\frac{5(x + 2)}{4(x – 2)}$.$\frac{(-2)(x – 2)}{x + 2}$ = $\frac{5(x + 2)(-2)(x – 2)}{4(x – 2)(x + 2)}$ = $\frac{-5}{2}$;
b) $\frac{x^{2} – 36}{2x + 10}$.$\frac{3}{6 – x}$ = $\frac{(x – 6)(x + 6)}{2(x + 5)}$.$\frac{(-3)}{x – 6}$ = $\frac{(x – 6)(x + 6)(-3)}{2(x + 5)(x – 6)}$ = $\frac{-3(x + 6)}{2(x + 5)}$.
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