Answer
$x^3+3x^2+3x+1$
Work Step by Step
$$(x+1)^3$$ $$=(x+1)(x+1)(x+1)$$ $$=(x+1)[(x\times x)+(x\times 1)+(1\times x)+(1\times 1)]$$ $$=(x+1)(x^2+x+x+1)$$ $$=(x+1)(x^2+2x+1)$$ $$=(x\times x^2)+(x\times 2x)+(x\times 1)+(1\times x^2)+(1\times 2x)+(1\times 1)$$ $$=x^3+2x^2+x+x^2+2x+1$$ $$=x^3+3x^2+3x+1$$
