Question

alguem sabe ----> [2x + y ]² - 6xy - [x - y]²

Answer 1

(2x+y)2 - 6xy
1.1
6xy

(2x+y)2   =  4x2+4xy+y2

(4x2 - 2xy + y2) - (x - y)2

4x2-2xy+y2 - (x-y)2  2.1     (x-y)2   =  x2-2xy+y2

3x2