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16. 若$\frac{4a - 1}{(a + 2)(a - 1)} = \frac{m}{a + 2} + \frac{n}{a - 1}$，则( ).
(A) $m = 4$，$n = -1$ (B) $m = 5$，$n = -1$
(C) $m = 3$，$n = 1$ (D) $m = 4$，$n = 1$
(A) $m = 4$，$n = -1$ (B) $m = 5$，$n = -1$
(C) $m = 3$，$n = 1$ (D) $m = 4$，$n = 1$
答案
17. 计算：
(1) $\frac{(ab^{2})^{3}}{(-ab)^{5}} + \frac{b}{a^{2}}$； (2) $\frac{a^{2} - ab}{a^{2}} \div \frac{a^{2} - b^{2}}{ab}$；
(3) $(\frac{x}{x + y} + \frac{2y}{x + y}) \cdot \frac{xy}{x + 2y} \div (\frac{1}{x} + \frac{1}{y})$；
(4) $(\frac{a}{a - b} - \frac{a^{2}}{a^{2} - 2ab + b^{2}}) \div (\frac{a}{a + b} - \frac{a^{2}}{a^{2} - b^{2}})$.
(1) $\frac{(ab^{2})^{3}}{(-ab)^{5}} + \frac{b}{a^{2}}$； (2) $\frac{a^{2} - ab}{a^{2}} \div \frac{a^{2} - b^{2}}{ab}$；
(3) $(\frac{x}{x + y} + \frac{2y}{x + y}) \cdot \frac{xy}{x + 2y} \div (\frac{1}{x} + \frac{1}{y})$；
(4) $(\frac{a}{a - b} - \frac{a^{2}}{a^{2} - 2ab + b^{2}}) \div (\frac{a}{a + b} - \frac{a^{2}}{a^{2} - b^{2}})$.
答案
