Question

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Explanation:

Step1: Distribute $5x$ to each term

$5x \cdot 9x^2 + 5x \cdot (-4x) + 5x \cdot (-8)$
$= 45x^3 - 20x^2 - 40x$

Step2: Distribute $-7$ to each term

$-7 \cdot 9x^2 + (-7) \cdot (-4x) + (-7) \cdot (-8)$
$= -63x^2 + 28x + 56$

Step3: Combine all distributed terms

$45x^3 - 20x^2 - 40x - 63x^2 + 28x + 56$

Step4: Combine like terms

$45x^3 + (-20x^2 -63x^2) + (-40x +28x) + 56$
$= 45x^3 -83x^2 -12x +56$

Answer:

$45$ $x^3$ $+$ $-83$ $x^2$ $+$ $-12$ $x$ $+$ $56$