Question

simplifica as expressões

a) (a - b)² - (a + b) . (a - b) =

b) (x - y)² + ( x + y )² - 2y² =

Answer 1

a) (a - b)² - (a + b) . (a - b) = (a - b)( a- b ) - (a + b)(a - b) 


(a - b)( a + b ) - (a - b)(a - b) ==> a² - b² - ( a² - 2ab + b² )

a² - b² - a² + 2ab - b² ==>  2ab
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b) (x - y)² + ( x + y )² - 2y² =

x² - 2xy + y² + x² +2xy + y² - 2y² ==> 2x²