(1)x/3y与3x/2y² (2)x-y/2x+2y与xy/(x+y)²
∵公分母为 6y² ∵公分母为2(x+y)²
∴x/3y= 2xy/6y² ∴x-y/2x+2y=(x-y)(x+y)/2(x+y)²
3x/2y²= 9/6y² xy/(x+y)²=2xy/2(x+y)²
(3)2mn/4m²-9与2m-3/2m+3
∵公分母为4m²-9
∴2mn/4m²-9=2mn/4m²-9
2m-3/2m+3=(2m-3)²/4m²-9
(1)x/3y与3x/2y² (2)x-y/2x+2y与xy/(x+y)²
∵公分母为 6y² ∵公分母为2(x+y)²
∴x/3y= 2xy/6y² ∴x-y/2x+2y=(x-y)(x+y)/2(x+y)²
3x/2y²= 9/6y² xy/(x+y)²=2xy/2(x+y)²
(3)2mn/4m²-9与2m-3/2m+3
∵公分母为4m²-9
∴2mn/4m²-9=2mn/4m²-9
2m-3/2m+3=(2m-3)²/4m²-9