16) the revenue (in thousands of dollars) from producing x units of an item is modeled by
r(x) = 5x - 0.0005x2. find the marginal revenue at x = 1000.

17) the total cost to produce x units of paint is c(x) = (5x + 3)(7x + 4). find the marginal
average cost function.

Part 16) The marginal revenue is $4,000

Part 17) The marginal average cost function is (70x+41)

Step-by-step explanation:

Part 16) we know that

The marginal revenue function is simply the derivative of the revenue function

we have

Find  

For x=1,000 units

substitute

Remember that the units is in thousands of dollars

therefore

The marginal revenue is $4,000

Part 17) we know that

The marginal average cost function is simply the derivative of the average cost function

we have

Applying the distributive property

Find the derivative

therefore

The marginal average cost function is (70x+41)

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x