Question

(mack-sp) se (x-y)² - (x-y)² = 140, então x. y é igual a? ​

Answer 1

$(\text x+\text y)^2-\text(\text x-\text y)^2=140 \\\\ \text x^2+2\text{x.y}+\text y^2-(\text x^2-2\text{x.y}+\text y^2) = 140 \\\\ \text x^2+2\text {x.y}+\text y^2-\text x^2+2\text {x.y}-\text y^2 \\\\ 4\text {x.y} = 140 \\\\\\ \text{x.y}= \displaystyle \frac{140}{4} \\\\\\ \huge\boxed{\ \text{x.y} = 35\ }\checkmark$

letra d

Answer 2

Resposta:

Aí está

Explicação passo-a-passo:

espero ter ajudado qualquer coisa conte comigo

:-)