Question

初二数学分式通分题

要过程（1）x-y/2x+2y与xy/（x+y）² （2）6c/a²b与c/3ab² （3）x-y/2x+2y与xy/（x+y）² （4）2mn/4m²-9与2m-3/2m+3

Answer 1

（1）x-y/2x+2y=(x-y)/2(x+y)=(x-y)(x+y)/2(x+y)^2
xy/（x+y)^2=2xy/2(x+y)^2
（2）6c/a²b=18bc/3a^2b^2
c/3ab²=ac/3a^2b^2
（3）x-y/2x+2y=(x-y)/2(x+y)=(x-y)(x+y)/2(x+y)^2
xy/（x+y)^2=2xy/2(x+y)^2
（4）2mn/4m²-9=2mn/(2m+3)(2m-3)
2m-3/2m+3=(2m-3)^2/(2m+3)(2m-3)

Answer 2

（1）x-y/2x+2y=(x+y)(x-y)/2（x+y）² xy/（x+y）²
（2）6c/a²b=18bc/3a²b² ac/3a²b²
(3)与（1）相同
（4）2mn/4m²-9 ( 2m-3）² /(2m+3)(2m-3)

Answer 3

（1） 2(x+y）的平方