Answer:
$68.44 for each additional belt
Step-by-step explanation:
The cost and revenue functions are:
[tex]C(x) = 970+12x - 0.076x^2\\R(x) =43x^{\frac{3}{4}}[/tex]
The profit function, P(x), is given by subtracting the cost function from the revenue function.
[tex]P(x) = R(x) - C(x)\\P(x)=43x^{\frac{3}{4}}+0.076x^2-12x-970\\[/tex]
The derivate of the profit function gives us the rate at which profit changes:
[tex]\frac{dP(x)}{dx} =P'(x)=32.25x^{\frac{-1}{4}}+0.152x-12\\[/tex]
For x = 484, the rate of change is:
[tex]P'(484)=32.25*484^{\frac{-1}{4}}+0.152*484-12\\P'(484) = \$68.44/belt[/tex]
Profit is increasing by $68.44 for each additional belt