y²分之（x²-2xy+y²）除以xy分之（y²-xy）乘xy²,其中x=4,y=3.

y²分之（x²-2xy+y²）除以xy分之（y²-xy）乘xy²,其中x=4,y=3.
y²分之（x²-2xy+y²）除以xy分之（y²-xy）乘xy²,其中x=4,y=3.

y²分之（x²-2xy+y²）除以xy分之（y²-xy）乘xy²,其中x=4,y=3.
（x²-2xy+y²)/y²÷（y²-xy）/xy *xy²
=(x-y)²/y²*xy/(y²-xy) *xy²
=(x-y)²*xy/y(y-x) *x
=(y-x)*x²
=(3-4)*4²
=-16

原式=(x-y)²/y²*xy/[-y(x-y)]*xy²
=-x(x-y)/y²*xy²
=-x²(x-y)
=-x³+x²y