[(x+y)^2-(x-y)^2 ]除以2xy

问题描述:

[(x+y)^2-(x-y)^2 ]除以2xy

[(x+y)^2-(x-y)^2 ]除以2xy
=(x+y+x-y)(x+y-x+y)÷2xy
=2x×2y÷2xy
=2