Find $ \left(x-6\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}{ 6 }$.

$$ \begin{aligned}\left(x-6\right)^2 = \color{blue}{x^2} -2 \cdot x \cdot 6 + \color{red}{6^2} = x^2-12x+36\end{aligned} $$

Multiply each term of $ \left( \color{blue}{x+8}\right) $ by each term in $ \left( x+1\right) $.

$$ \left( \color{blue}{x+8}\right) \cdot \left( x+1\right) = x^2+x+8x+8 $$

Combine like terms:

$$ x^2+ \color{blue}{x} + \color{blue}{8x} +8 = x^2+ \color{blue}{9x} +8 $$

Multiply each term of $ \left( \color{blue}{x^2+9x+8}\right) $ by each term in $ \left( x^2-12x+36\right) $.

$$ \left( \color{blue}{x^2+9x+8}\right) \cdot \left( x^2-12x+36\right) = x^4-12x^3+36x^2+9x^3-108x^2+324x+8x^2-96x+288 $$

Combine like terms:

$$ x^4 \color{blue}{-12x^3} + \color{red}{36x^2} + \color{blue}{9x^3} \color{green}{-108x^2} + \color{orange}{324x} + \color{green}{8x^2} \color{orange}{-96x} +288 = \\ = x^4 \color{blue}{-3x^3} \color{green}{-64x^2} + \color{orange}{228x} +288 $$

Multiply each term of $ \left( \color{blue}{x^4-3x^3-64x^2+228x+288}\right) $ by each term in $ \left( x-13\right) $.

$$ \left( \color{blue}{x^4-3x^3-64x^2+228x+288}\right) \cdot \left( x-13\right) = \\ = x^5-13x^4-3x^4+39x^3-64x^3+832x^2+228x^2-2964x+288x-3744 $$

Combine like terms:

$$ x^5 \color{blue}{-13x^4} \color{blue}{-3x^4} + \color{red}{39x^3} \color{red}{-64x^3} + \color{green}{832x^2} + \color{green}{228x^2} \color{orange}{-2964x} + \color{orange}{288x} -3744 = \\ = x^5 \color{blue}{-16x^4} \color{red}{-25x^3} + \color{green}{1060x^2} \color{orange}{-2676x} -3744 $$