Question
Question: If \(\int_{}^{}\frac{\cos 4x + 1}{\cot x–\tan x}\)dx = k cos 4x + c, then...
If ∫cotx–tanxcos4x+1dx = k cos 4x + c, then
A
k = – ½
B
k = – 1/8
C
k = – ¼
D
None of these
Answer
k = – 1/8
Explanation
Solution
=∫(2x+4)x2+4x+3dx−∫x2+4x+3dx. cos x. sin x dx
= =I1−I2,(say)sin 2x dx = – 81cos4x + c \ k = – 1/8