Step-by-step explanation:
the perimeter of a rectangle is
2×length + 2×width =
2×(x + 10y) + 2×(7x² - x + 9y) =
2x + 20y + 14x² - 2x + 18y =
14x² + 38y
If you can't figure out how to do it, you can always use your answer choices, so for example, use choice a (21 degrees). Plug in 21 for x for both equations. So for the first equation that would be 7(21)-1= 146 and second equation 3(2)-9= 54. Then you would add the results, 146+54=200. In that case, choice 21 is wrong because both of these angles should equal to 180 since it is a supplementary angle. I hope that helped.
What is the full question?
Answer:
a. D'(p) = -10p - 6
b. There is a decrease of 96 units of demand for each dollar increase
Step-by-step explanation:
The demand function is:

(a) The derivate of the demand function with respect to price gives us the rate of change of demand:

(b) When p = $9, the rate of change of demand is:

This means that, when p = $9, there is a decrease of 96 units of demand for each dollar increase.