Answer:
B
Step-by-step explanation:
4 or greater: 1/2 (4,5,6)
4 or smaller: 2/3 (1,2,3,4)
1/2 * 2/3 = 2/6
2/6 = 1/3
1/3 = 0.333
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.
If a^ x = b then:
x = log_{a}b
For:
4^{7} = 16384 \\ log _{4}16384 = 7
A=9,805×(1+0.085×7÷12)
A=10,291.16
Subtract a number from the next number.
39 - 45 = -6
Answer: B. -6