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

$$ \left( \color{blue}{x^2+7}\right) \cdot \left( 4x-3\right) = 4x^3-3x^2+28x-21 $$

Multiply each term of $ \left( \color{blue}{4x^3-3x^2+28x-21}\right) $ by each term in $ \left( 5-2x\right) $.

$$ \left( \color{blue}{4x^3-3x^2+28x-21}\right) \cdot \left( 5-2x\right) = 20x^3-8x^4-15x^2+6x^3+140x-56x^2-105+42x $$

Combine like terms:

$$ \color{blue}{20x^3} -8x^4 \color{red}{-15x^2} + \color{blue}{6x^3} + \color{green}{140x} \color{red}{-56x^2} -105+ \color{green}{42x} = \\ = -8x^4+ \color{blue}{26x^3} \color{red}{-71x^2} + \color{green}{182x} -105 $$

Multiply each term of $ \left( \color{blue}{-8x^4+26x^3-71x^2+182x-105}\right) $ by each term in $ \left( x-1\right) $.

$$ \left( \color{blue}{-8x^4+26x^3-71x^2+182x-105}\right) \cdot \left( x-1\right) = \\ = -8x^5+8x^4+26x^4-26x^3-71x^3+71x^2+182x^2-182x-105x+105 $$

Combine like terms:

$$ -8x^5+ \color{blue}{8x^4} + \color{blue}{26x^4} \color{red}{-26x^3} \color{red}{-71x^3} + \color{green}{71x^2} + \color{green}{182x^2} \color{orange}{-182x} \color{orange}{-105x} +105 = \\ = -8x^5+ \color{blue}{34x^4} \color{red}{-97x^3} + \color{green}{253x^2} \color{orange}{-287x} +105 $$