登录
1. 计算$\frac{a+1}{a+2}+\frac{1}{a+2}$的结果是（
A.1
B.$\frac{2}{a+2}$
C.$a+2$
D.$\frac{a}{a+2}$
A
）.A.1
B.$\frac{2}{a+2}$
C.$a+2$
D.$\frac{a}{a+2}$
答案
1. A
2. 下列计算正确的是(
A.$\frac{a}{x}+\frac{b}{x}=\frac{a+b}{2x}$
B.$\frac{a}{x-y}-\frac{a}{y-x}=0$
C.$2+\frac{1}{a}=\frac{3}{a}$
D.$\frac{x}{x-y}-\frac{y}{x-y}=1$
D
).A.$\frac{a}{x}+\frac{b}{x}=\frac{a+b}{2x}$
B.$\frac{a}{x-y}-\frac{a}{y-x}=0$
C.$2+\frac{1}{a}=\frac{3}{a}$
D.$\frac{x}{x-y}-\frac{y}{x-y}=1$
答案
2. D
3. (1)$\frac{b}{a}-\frac{a}{b}=$
$\frac{b^2-a^2}{ab}$
； (2)$\frac{1}{x-1}-\frac{x^2}{x-1}=$$-x-1$
。答案
3. (1) $\frac{b^2-a^2}{ab}$ (2) $-x-1$
4. 化简：$\frac{x^2 + xy}{xy} + \frac{xy - x^2}{xy} =$
2
答案
4. 2
5. 计算:
(1)$\frac{a-1}{a-b}-\frac{a}{a-b}+\frac{2}{a-b};$
(2)$\frac{1}{2c^2d}-\frac{1}{3cd^2};$
(3)$\frac{1}{x+2}+\frac{2}{x^2+2x};$
(4)$\frac{2x}{x^2-36y^2}-\frac{1}{x+6y}.$
(1)$\frac{a-1}{a-b}-\frac{a}{a-b}+\frac{2}{a-b};$
(2)$\frac{1}{2c^2d}-\frac{1}{3cd^2};$
(3)$\frac{1}{x+2}+\frac{2}{x^2+2x};$
(4)$\frac{2x}{x^2-36y^2}-\frac{1}{x+6y}.$
答案
(1) $\frac{1}{a-b}$ (2) $\frac{3d-2c}{6c^2d^2}$ (3) $\frac{1}{x}$ (4) $\frac{1}{x-6y}$
