Question

RÚT GỌN CÁC BIỂU THỨC SAU 

MẤY BẠN GIÚP MK VS Ạ AI NHANH MK VOTE NHA

Answer 1

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

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

\(=2y^2\)

b: Ta có: \(\left(x+1\right)^3-\left(x-1\right)\left(x^2+x+1\right)-3x\left(x+1\right)\)

\(=x^3+3x^2+3x+1-x^3+1-3x^2-3x\)

=2

Answer 2

c) \(\left(x+2y\right)\left(x^2-2xy+4y^2\right)-\left(x-2y\right)\left(x^2+2xy+4y^2\right)+2y^3\)

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

\(=x^3+8y^3-x^3+8y^3+2y^3\)

\(=8y^3+8y^3+2y^3\)

\(=18y^3\)