

InterviewSolution
Saved Bookmarks
1. |
If `int(tan^(9)x)dx=f(x)+log|cosx|,` where f(x) is a polynomial of degree n in tan x, then the value of n isA. 6B. 7C. 8D. none of these |
Answer» Correct Answer - C Let `I_(9)=int tan^(9)xdx=int tan^(7)x(sec^(2)x-1)dx` `"i.e., "I_(9)=(tan^(8)x)/(8)-I_(7)` `"Similarly, "I_(7)=(tan^(6)x)/(6)-I_(5)` ………………………………….. ……………………………….. ………………………………. `I_(3)=(tan^(2)x)/(2)-I_(1)=(tan^(2)x)/(2)-int tanxdx` `=(tan^(2)x)/(2)+log|cos x|` `therefore I_(9)=" (a polynomial of degree 8 in tan x)"+ log |cos x|+C` |
|