Question

a, (x^2 + 2x + 3)(x + 2)

b, (x^2 + xy + y^2)(x - y)

c, (x + y)(x^2 - xy + y^2)

 

Answer 1

a, \(\left(x^2+2x+3\right)\left(x+2\right)=x^3+2x^2+3x+2x^2+4x+6=x^3+4x^2+7x+6\)

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

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

Answer 2

a: Ta có: \(\left(x^2+2x+3\right)\left(x+2\right)\)

\(=x^3+2x^2+2x^2+4x+3x+6\)

\(=x^3+4x^2+7x+6\)

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

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

\(=x^3-y^3\)

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

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

\(=x^3+y^3\)