[(x-3y)²-(x+3y)²]÷(-2xy)

问题描述:

[(x-3y)²-(x+3y)²]÷(-2xy)

[(x-3y)²-(x+3y)²]÷(-2xy)
=[(x-3y)+(x+3y)][(x-3y)-(x+3y)]÷(-2xy)
=2x×(-6y)÷(-2xy)
=6