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MTH 102 MTH 102 Past Questions Objective Question

Question

Which of the following option best describes the reduction formula for \(V_n = \int \csc^n x\,dx\), where \(n \ge 2\)?
Options
A \(-\frac{1}{n-1}\csc^{n-2}x \cot x + \frac{n-2}{n-1}V_{n-2}\)
Correct Answer
B \(-\frac{1}{1-n}\csc^{n-2}x \cot x - \frac{n-2}{n-1}V_{n-2}\)
C \(-\frac{1}{n-1}\csc^{n-2}x \tan x + \frac{n-2}{n-1}V_{n-2}\)
D None.
Correct Answer

Option A is the correct answer.

Detailed Explanation

The standard reduction formula for (\int \csc^n x\,dx) is given by:(\int \csc^n x\,dx = -\frac{\csc^{n-2}x \cot x}{n-1} + \frac{n-2}{n-1} \int \csc^{n-2}x\,dx)If we denote (V_n = \int \csc^n x\,dx), then the formula can be written as:(V_n = -\frac{1}{n-1}\csc^{n-2}x \cot x + \frac{n-2}{n-1}V_{n-2}).This matches option A.

Hint

Recall the reduction formula for powers of cosecant function.

Question Info