Ok, so 1 is a whole number. 1/5 is a fraction of 1. So you want to subtract 1/5 from 1. The number 1 is equal to 5/5. So if you subtract 1/5 from 5/5 you are left with 4/5. You do the same with the second one, just subtract 3/5 from 5/5 to get your answer.
Answer:
a
Step-by-step explanation:
(3x-14)+9x=90, thus,
((3x-14)+9x)+90=180
90+90=180
You multiply 55.25 by 0.18. You get 9.945 and then you add it to 55.25. You should get 65.195. Round it to $65.20. That's your answer.
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.
Your method is right so u already know how to do it