Find $ \left(x+3\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}{ 3 }$.

$$ \begin{aligned}\left(x+3\right)^2 = \color{blue}{x^2} +2 \cdot x \cdot 3 + \color{red}{3^2} = x^2+6x+9\end{aligned} $$

Find $ \left(x-4\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}{ 4 }$.

$$ \begin{aligned}\left(x-4\right)^2 = \color{blue}{x^2} -2 \cdot x \cdot 4 + \color{red}{4^2} = x^2-8x+16\end{aligned} $$

Multiply each term of $ \left( \color{blue}{2x-1}\right) $ by each term in $ \left( x^2+6x+9\right) $.

$$ \left( \color{blue}{2x-1}\right) \cdot \left( x^2+6x+9\right) = 2x^3+12x^2+18x-x^2-6x-9 $$

Combine like terms:

$$ 2x^3+ \color{blue}{12x^2} + \color{red}{18x} \color{blue}{-x^2} \color{red}{-6x} -9 = 2x^3+ \color{blue}{11x^2} + \color{red}{12x} -9 $$

Multiply each term of $ \left( \color{blue}{2x^3+11x^2+12x-9}\right) $ by each term in $ \left( x^2-8x+16\right) $.

$$ \left( \color{blue}{2x^3+11x^2+12x-9}\right) \cdot \left( x^2-8x+16\right) = \\ = 2x^5-16x^4+32x^3+11x^4-88x^3+176x^2+12x^3-96x^2+192x-9x^2+72x-144 $$

Combine like terms:

$$ 2x^5 \color{blue}{-16x^4} + \color{red}{32x^3} + \color{blue}{11x^4} \color{green}{-88x^3} + \color{orange}{176x^2} + \color{green}{12x^3} \color{blue}{-96x^2} + \color{red}{192x} \color{blue}{-9x^2} + \color{red}{72x} -144 = \\ = 2x^5 \color{blue}{-5x^4} \color{green}{-44x^3} + \color{blue}{71x^2} + \color{red}{264x} -144 $$