х+у х-у
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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)