CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2010

  • question_answer
    \[\int_{-100}^{100}{f(x)}dx\]is equal to

    A)  \[\int_{-100}^{100}{f({{x}^{2}})}\,dx\]

    B)  \[\int_{-100}^{100}{f(-{{x}^{2}})}\,dx\]

    C)  \[\int_{-100}^{100}{f\left( \frac{1}{x} \right)}\,dx\]

    D)  \[\int_{-100}^{100}{f(-x)}\,dx\]

    E)  \[\int_{-100}^{100}{[f(x)+f(-x)}]\,dx\]

    Correct Answer: D

    Solution :

    \[\int_{-100}^{100}{f(x)dx}=2\int_{0}^{100}{f(x)}dx\] if             \[f(-x)=f(x)\]                                      ?.(i)                 \[=2\int_{0}^{100}{f(-x)}dx\]                 \[=\int_{-100}^{100}{f(-x)}dx\] Alternate \[=\int_{-100}^{100}{f(x)}dx=\int_{-100}^{100}{f(100-100-x)}dx\]                                 \[=\int_{-100}^{100}{f(x)}dx\] [Using the property\[\int_{a}^{b}{f(x)}dx\]                 \[=\int_{a}^{b}{f(a+b-x)}dx]\]  


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