第6页 - 江苏版启东中学作业本八年级数学（上下册）

$=\frac {ab^2}{6ac}$

$=\frac {b^2}{6c}$

$=\frac {3xy^2}{4z^2} · (- \frac {8z^2}{y} )$

$=-\frac {24xy^2z^2}{4z^2y}$

$=-6 xy$

$=\frac {(-2m)^3}{(3n^2)^3}$

$=- \frac {8\ \mathrm {m^3}}{27n^6}$

$=\frac {2}{(x+1)(x-1)} · (x-1)$

$=\frac {2}{x+1}$

$=\frac {(x+1)(x-1)}{x(x+2)} · \frac {x}{x-1}$

$= \frac {x+1}{x+2}$

$=\frac {(x+1)^2}{(x+1)(x-1)} · \frac {1}{x+1}$

$=\frac {1}{x-1}$

$=\frac {(x+2)(x-2)}{4x^2y} · \frac {6x^3y}{3(x+2)}$

$=\frac {x(x-2)}{2}$

$=\frac {x}{(x+1)(x-1)} · \frac {x(x+1)}{x^2}$

$=\frac 1{x-1}$

$=\frac {(x+1)^2}{(x+1)(x-1)} · \frac {x(x-1)}{x+1}$

$=x$

$=\frac {a+3}{1-a} · \frac {(a-1)^2}{a(a+3)}$

$=\frac {a+3}{1-a} · \frac {(1-a)^2}{a(a+3)}$

$=\frac {1-a}a$

$=\frac {\mathrm {m^2}}{n^2} · \frac {n}{m} · (- \frac {n^2}{m} )$

$=\frac {m}{n} · (- \frac {n^2}{m} )$

$=-n$

$=\frac {ab^2}{2c^2} · \frac {4cd}{-3a^2b^2} · \frac {-3}{2d}$

$=\frac 1{ac}$

$=- \frac {a-1}{a+2} · \frac {(a+2)(a-2)}{(a-1)^2} · (a+1)(a-1)$

$=-(a-2)(a+1)$

$=-a^2+a+2$

$=-x(x-y) · \frac {xy}{(x-y)^2} · \frac {x-y}{x^2}$

$=-y$