Question

a expressao (x-y)2-(x+y)2 é equivalente a??

Answer 1

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$(x-y)^2-(x+y)^2= \\ x^2-2xy+y^2-(x^2+2xy+y^2)= \\ x^2-2xy+y^2-x^2-2xy-y^2= \\ x^2-x^2+y}2-y^2-2xy-2xy= \\ -4xy$

Answer 2

$(x - y)^2 - (x + y)^2 \\ \\ (x - y)(x - y) - (x + y)(x+y) \\ \\ (x^2 - 2xy + y^2) -(x^2 + 2xy + y^2) \\ \\ x^2 - 2xy + y^2 - x^2 - 2xy - y^2 \\ \\ => -4xy$