Question

Rút gọn biểu thức.

a)M=(x+3y)²-(x-3y)²

b)Q=(x-y)²-4(x-y)(x+2y)+4(x+2y)²

Answer 1

a) M = (x + 3y)² - (x - 3y)²

= [(x + 3y) - (x - 3y)][(x + 3y) + (x - 3y)]

= (x + 3y - x + 3y)(x + 3y + x - 3y)

= 6y.2x

= 12xy

Answer 2

b: Q=(x-y)^2-2(x-y)(2x+4y)+(2x+4y)^2

=(x-y-2x-4y)^2

=(-x-5y)^2

=x^2+10xy+25y^2