Question

Rút gọn các biểu thức sau:

      a) ( x + y)² + (x - y)²         b) ( x + y)² + (x - y)² + 2( x+ y) ( x- y)

      c) (2+3y)²-(2x-3y)²-12xy         d) ( 3x + 1)² -  (3x - 1)²

      e)(x+1)(x²-x+1)-(x-1)(x²+x+1)

Answer 1

a: \(=x^2+2xy+y^2+x^2-2xy+y^2=2x^2+2y^2\)

b: \(=\left(x+y+x-y\right)^2=\left(2x\right)^2=4x^2\)

d: \(=9x^2+6x+1-9x^2+6x-1=12x\)