完全立方公式[ (x-y)^3 × (√x+√y)^(-3) + 3(x√y-y√x) ] / (x√x+y√y) 　　=[ (√_数学解答

完全立方公式
[ (x-y)^3 × (√x+√y)^(-3) + 3(x√y-y√x) ] / (x√x+y√y) 　　=[ (√x-√y)^3 + 3√xy × (√x-√y) ] / (x√x+y√y) 　　=(x√x-y√y) / (x√x+y√y)什么意思,没看明白

人气：492 ℃　时间：2020-01-29 13:01:49

解答

[ (x-y)^3 × (√x+√y)^(-3) + 3(x√y-y√x) ] / (x√x+y√y)=[ (x-y)^3 /(√x+√y)^3 + 3√(xy) × (√x-√y) ] / (x√x+y√y) (注：中括弧中第2项提取√(xy) )={ [(x-y)/(√x+√y)]^3 + 3√(xy) × (√x-√y) } /...