Question

desenvolva as expressões
$(x - y) {}^{2} - (x + y) {}^{2}$
outra
$(3 + ab) \times (ab - 3)$

Answer 1

(x - y)² - (x + y)²

= x² - 2xy + y² - (x² + 2xy + y²)

= x² - 2xy + y² - x² - 2xy - y²

= -4xy

(3 + ab) * (ab - 3)

= (ab + 3) * (ab - 3)

= a²b² - 9