Q204 · Practice questionTechnology-freeComplex familiar5 marks
QUESTION 204 (5 marks)
Let on .
a)[3 marks]
Determine exactly.
b)[2 marks]
Determine the mean value of f on the interval.
WORKED SOLUTION
5 marksPractice marking scheme
ANSWER
(a) . (b) .
Worked solution
(a) Use parts with u=ln x and dv=x dx:
At e this is , and at 1 it is -1/4. Their difference gives the answer.
(b) The mean value is the integral divided by the interval length e-1. Thus it is , rather than dividing by e.
Equivalent mathematically justified methods accepted.
Exact answers unless a decimal accuracy is specified.
Part a: Choose suitable parts.
Part a: Obtain the antiderivative.
Part a: Evaluate both endpoints.
Part b: Use the interval length e-1.
Part b: Give the exact mean value.
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