Question

giúp mình với ạ:(

Answer 1

a)

\(\left(x-y\right)\left(x+y\right)=x^2+xy-yx-y^2\\ =x^2-y^2=VP\)

b)

\(\left(x+y\right)^2\\ =\left(x+y\right)\left(x+y\right)\\ =x^2+xy+yx+y^2\\ =x^2+2xy+y^2=VP\)

c)

\(\left(x-y\right)^2=\left(x-y\right)\left(x-y\right)\\ =x^2-xy-yx+y^2\\ =x^2-2xy+y^2=VP\)

d)

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

e)

\(\left(x-y\right)\left(x^3+x^2y+xy^2+y^3\right)\\ =x^4+x^3y+x^2y^2+xy^3-yx^3-x^2y^2-xy^3-y^4\\ =x^4-y^4=VP\)