Question

Rút gọn biểu thức:

a) A = (x + y)² – (x – y)²

b) B = (x +2)² + 2.(x + 2).(x - 3) +( x - 3)²

c) C = (x +2)² - 2.(x + 2).(x + 3) +( x + 3)²

Answer 1

a, \(A=x^2+2xy+y^2-x^2+2xy-y^2=4xy\)

b, \(B=\left(x+2+x-3\right)^2=\left(2x-1\right)^2=4x^2-4x+1\)

c, \(C=\left(x+2-x-3\right)^2=1\)

Answer 2

\(A=\left(x+y+x-y\right)\left(x+y-x+y\right)=2x.2y=4xy.\\ B=\left(x+2+x-3\right)^2=\left(2x-1\right)^2.\\ C=\left(x+2-x-3\right)^2=\left(-1\right)^2=1.\)