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

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

Combine like terms:

$$ x^2 \color{blue}{-2x} \color{blue}{-x} +2 = x^2 \color{blue}{-3x} +2 $$

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

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

Combine like terms:

$$ x^3 \color{blue}{-4x^2} \color{blue}{-3x^2} + \color{red}{12x} + \color{red}{2x} -8 = x^3 \color{blue}{-7x^2} + \color{red}{14x} -8 $$

Multiply each term of $ \left( \color{blue}{x^3-7x^2+14x-8}\right) $ by each term in $ \left( x-7\right) $.

$$ \left( \color{blue}{x^3-7x^2+14x-8}\right) \cdot \left( x-7\right) = x^4-7x^3-7x^3+49x^2+14x^2-98x-8x+56 $$

Combine like terms:

$$ x^4 \color{blue}{-7x^3} \color{blue}{-7x^3} + \color{red}{49x^2} + \color{red}{14x^2} \color{green}{-98x} \color{green}{-8x} +56 = \\ = x^4 \color{blue}{-14x^3} + \color{red}{63x^2} \color{green}{-106x} +56 $$

Multiply each term of $ \left( \color{blue}{x^4-14x^3+63x^2-106x+56}\right) $ by each term in $ \left( x-14\right) $.

$$ \left( \color{blue}{x^4-14x^3+63x^2-106x+56}\right) \cdot \left( x-14\right) = \\ = x^5-14x^4-14x^4+196x^3+63x^3-882x^2-106x^2+1484x+56x-784 $$

Combine like terms:

$$ x^5 \color{blue}{-14x^4} \color{blue}{-14x^4} + \color{red}{196x^3} + \color{red}{63x^3} \color{green}{-882x^2} \color{green}{-106x^2} + \color{orange}{1484x} + \color{orange}{56x} -784 = \\ = x^5 \color{blue}{-28x^4} + \color{red}{259x^3} \color{green}{-988x^2} + \color{orange}{1540x} -784 $$