Answer:
a) Y(x) = {900, x≤30; 900-40(x-30), x>30}
b) T(x) = {900x, x≤30; 2100x-40x², x>30}
c) dT/dx = {900, x≤30; 2100-80x, x>30}
Step-by-step explanation:
a) The problem statement gives the function for x ≤ 30, and gives an example of evaluating the function for x = 35. So, replacing 35 in the example with x gives the function definition for x > 30.

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b) The yield per acre is the product of the number of trees and the yield per tree:
T(x) = x·Y(x)

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c) The derivative is ...

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The attached graph shows the yield per acre (purple, overlaid by red for x<30), the total yield (black), and the derivative of the total yield (red). You will note the discontinuity in the derivative at x=30, where adding one more tree per acre suddenly makes the rate of change of yield be negative.
Find the number that both can be divided by i.e. the common denominator of 56/8 is 8 because 56 is divisible by 8 and 8 is also divisible by 8.
so by finding the common denominator and dividing the fraction, the equation would look like this: 7/1
Answer:

Step-by-step explanation:
Slope/Gradient = 
P = (-8 , 3) (x1, y1)
Q = (-6 , 2) (x2, y2)
Slope =
=
=
= 
Answer:
The rate of change is
6.2 ×
= 0.37
Answer ^ ^ ^ ^ ^ ^ ^
Explanation: it broke itself