Question

rút gọn biểu thức

a)\(\left(x+y\right)^2-\left(x-y\right)^2-2x\left(2y-x\right)\)

b)\(\left(x-2\right)^2+\left(x+3\right)^2-2\left(x-2\right)\left(x+3\right)\)

Answer 1

b) \(=\left(x-2\right)^2-2\left(x-2\right)\left(x+3\right)+\left(x+3\right)^2\) (hằng đẳng thức số 2)

\(=\left[\left(x-2\right)-\left(x+3\right)\right]^2\)

\(=\left[x-2-x-3\right]^2\)

\(=\left[-5\right]^2=25\)

Answer 2

a)

b)

Answer 3

a)\(=\left(x^2+2xy+y^2\right)-\left(x^2-2xy+y^2\right)-\left(4xy-2x^2\right)\)

\(=x^2+2xy+y^2-x^2+2xy-y^2-4xy+2x^2\)

\(=2x^2\)