Question

(x + y + z)³ - x³ - y³ - z³

giúp mình nha

Answer 1

\(=\left(x+y+z-x\right)\left[\left(x+y+z\right)^2+\left(x+y+z\right)x+x^2\right]-\left(y+z\right)\left(y^2-yz+z^2\right)\)

\(=\left(y+z\right)\left(x^2+y^2+z^2+2xy+2yz+2zx+x^2+xy+xz+x^2-y^2+yz-z^2\right)\)

\(=\left(y+z\right)\left(3x^2+3xy+3yz+3zx\right)\)\(=\left(y+z\right)\left[3x\left(x+y\right)+3z\left(x+y\right)\right]\)

\(=3\left(x+y\right)\left(y+z\right)\left(z+x\right)\)

k mk nha ^^

Answer 2

=x^3+y^3+z^3-x^3-y^3-z^3 

=(x^3-x^3)+(y^3-y^3)+(z^3-z^3)

=0+0+0

=0