Find $ \left(s+8\right)^2 $ using formula.

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

where $ A = \color{blue}{ s } $ and $ B = \color{red}{ 8 }$.

$$ \begin{aligned}\left(s+8\right)^2 = \color{blue}{s^2} +2 \cdot s \cdot 8 + \color{red}{8^2} = s^2+16s+64\end{aligned} $$

Multiply each term of $ \left( \color{blue}{x-2}\right) $ by each term in $ \left( x+1\right) $.

$$ \left( \color{blue}{x-2}\right) \cdot \left( x+1\right) = x^2+x-2x-2 $$Multiply $ \color{blue}{12} $ by $ \left( s^2+16s+64\right) $ $$ \color{blue}{12} \cdot \left( s^2+16s+64\right) = 12s^2+192s+768 $$

Combine like terms:

$$ x^2+ \color{blue}{x} \color{blue}{-2x} -2 = x^2 \color{blue}{-x} -2 $$

Multiply each term of $ \left( \color{blue}{x^2-x-2}\right) $ by each term in $ \left( x+10\right) $.

$$ \left( \color{blue}{x^2-x-2}\right) \cdot \left( x+10\right) = x^3+10x^2-x^2-10x-2x-20 $$

Combine like terms:

$$ x^3+ \color{blue}{10x^2} \color{blue}{-x^2} \color{red}{-10x} \color{red}{-2x} -20 = x^3+ \color{blue}{9x^2} \color{red}{-12x} -20 $$

Combine like terms:

$$ x^3+9x^2-12x \color{blue}{-20} +12s^2+192s+ \color{blue}{768} = x^3+12s^2+9x^2+192s-12x+ \color{blue}{748} $$