Find $ \left(x+2\right)^2 $ using formula.

$$ (A + B)^2 = \color{blue}{A^2} + 2 \cdot A \cdot B + \color{red}{B^2} $$

where $ A = \color{blue}{ x } $ and $ B = \color{red}{ 2 }$.

$$ \begin{aligned}\left(x+2\right)^2 = \color{blue}{x^2} +2 \cdot x \cdot 2 + \color{red}{2^2} = x^2+4x+4\end{aligned} $$

Multiply each term of $ \left( \color{blue}{x^2+4x+4}\right) $ by each term in $ \left( x0\right) $.

$$ \left( \color{blue}{x^2+4x+4}\right) \cdot \left( x0\right) = x^30x^2+4x^20x+4x0 $$

Combine like terms:

$$ x^3 \color{blue}{0x^2} + \color{blue}{4x^2} \color{red}{0x} + \color{red}{4x} 0 = x^3+ \color{blue}{4x^2} + \color{red}{4x} $$

Multiply each term of $ \left( \color{blue}{x^3+4x^2+4x}\right) $ by each term in $ \left( x-4\right) $.

$$ \left( \color{blue}{x^3+4x^2+4x}\right) \cdot \left( x-4\right) = x^4 -\cancel{4x^3}+ \cancel{4x^3}-16x^2+4x^2-16x $$

Combine like terms:

$$ x^4 \, \color{blue}{ -\cancel{4x^3}} \,+ \, \color{blue}{ \cancel{4x^3}} \, \color{green}{-16x^2} + \color{green}{4x^2} -16x = x^4 \color{green}{-12x^2} -16x $$

Multiply each term of $ \left( \color{blue}{x^4-12x^2-16x}\right) $ by each term in $ \left( x-8\right) $.

$$ \left( \color{blue}{x^4-12x^2-16x}\right) \cdot \left( x-8\right) = x^5-8x^4-12x^3+96x^2-16x^2+128x $$

Combine like terms:

$$ x^5-8x^4-12x^3+ \color{blue}{96x^2} \color{blue}{-16x^2} +128x = x^5-8x^4-12x^3+ \color{blue}{80x^2} +128x $$

Multiply each term of $ \left( \color{blue}{x^5-8x^4-12x^3+80x^2+128x}\right) $ by each term in $ \left( x-13\right) $.

$$ \left( \color{blue}{x^5-8x^4-12x^3+80x^2+128x}\right) \cdot \left( x-13\right) = \\ = x^6-13x^5-8x^5+104x^4-12x^4+156x^3+80x^3-1040x^2+128x^2-1664x $$

Combine like terms:

$$ x^6 \color{blue}{-13x^5} \color{blue}{-8x^5} + \color{red}{104x^4} \color{red}{-12x^4} + \color{green}{156x^3} + \color{green}{80x^3} \color{orange}{-1040x^2} + \color{orange}{128x^2} -1664x = \\ = x^6 \color{blue}{-21x^5} + \color{red}{92x^4} + \color{green}{236x^3} \color{orange}{-912x^2} -1664x $$