Х+у х-у _____ --- ____ х-у х+у упростить
=((x+y)(x+y) -(x-y)(x-y)) /(x-y)(x+y) =(x²+2xy+y² -(x²-2xy+y²)) /(x-y)(x+y) =(x²+2xy+y² -x²+2xy -y²) /(x-y)(x+y) =4xy /(x² -y²)