Find $ \left(2x+1\right)^2 $ using formula.

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

where $ A = \color{blue}{ 2x } $ and $ B = \color{red}{ 1 }$.

$$ \begin{aligned}\left(2x+1\right)^2 = \color{blue}{\left( 2x \right)^2} +2 \cdot 2x \cdot 1 + \color{red}{1^2} = 4x^2+4x+1\end{aligned} $$

Multiply each term of $ \left( \color{blue}{4x^2+4x+1}\right) $ by each term in $ \left( x-2\right) $.

$$ \left( \color{blue}{4x^2+4x+1}\right) \cdot \left( x-2\right) = 4x^3-8x^2+4x^2-8x+x-2 $$

Combine like terms:

$$ 4x^3 \color{blue}{-8x^2} + \color{blue}{4x^2} \color{red}{-8x} + \color{red}{x} -2 = 4x^3 \color{blue}{-4x^2} \color{red}{-7x} -2 $$

Multiply each term of $ \left( \color{blue}{4x^3-4x^2-7x-2}\right) $ by each term in $ \left( x+3\right) $.

$$ \left( \color{blue}{4x^3-4x^2-7x-2}\right) \cdot \left( x+3\right) = 4x^4+12x^3-4x^3-12x^2-7x^2-21x-2x-6 $$

Combine like terms:

$$ 4x^4+ \color{blue}{12x^3} \color{blue}{-4x^3} \color{red}{-12x^2} \color{red}{-7x^2} \color{green}{-21x} \color{green}{-2x} -6 = 4x^4+ \color{blue}{8x^3} \color{red}{-19x^2} \color{green}{-23x} -6 $$

Multiply each term of $ \left( \color{blue}{4x^4+8x^3-19x^2-23x-6}\right) $ by each term in $ \left( x-1\right) $.

$$ \left( \color{blue}{4x^4+8x^3-19x^2-23x-6}\right) \cdot \left( x-1\right) = 4x^5-4x^4+8x^4-8x^3-19x^3+19x^2-23x^2+23x-6x+6 $$

Combine like terms:

$$ 4x^5 \color{blue}{-4x^4} + \color{blue}{8x^4} \color{red}{-8x^3} \color{red}{-19x^3} + \color{green}{19x^2} \color{green}{-23x^2} + \color{orange}{23x} \color{orange}{-6x} +6 = \\ = 4x^5+ \color{blue}{4x^4} \color{red}{-27x^3} \color{green}{-4x^2} + \color{orange}{17x} +6 $$