CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2005

  • question_answer
    \[\int{{{\cos }^{-3/7}}x{{\sin }^{-11/7}}}x\,dx\]is equal to:

    A)  \[\log |{{\sin }^{4/7}}x|+c\]

    B)  \[\frac{4}{7}{{\tan }^{4/7}}x+c\]

    C)  \[\frac{-7}{4}{{\tan }^{-4/7}}x+c\]

    D)  \[\log |{{\cos }^{3/7}}x|+c\]

    E)  \[\frac{7}{4}{{\tan }^{-4/7}}x+c\]

    Correct Answer: C

    Solution :

    \[\int{{{\cos }^{-3/7}}}x{{\sin }^{-11/7}}x\,dx\] \[=\int{\frac{{{\sin }^{-11/7}}x}{{{\cos }^{-11/7}}x}}.{{\sec }^{2}}xdx\] \[=\int{{{\tan }^{-11/7}}}x{{\sec }^{2}}x\,dx\] Let          \[\tan x=t\] \[\Rightarrow \]               \[{{\sec }^{2}}xdx=dt\] \[\therefore \]  \[I=\int{{{t}^{-11/7}}dt}=-\frac{7}{4}{{\tan }^{-4/7}}x+c\]


You need to login to perform this action.
You will be redirected in 3 sec spinner