JEE Main & Advanced Mathematics Definite Integration Question Bank Fundamental definite integration, Definite integration by substitution

  • question_answer
    \[\left( \int_{\,0}^{\,a}{x\,dx} \right)\le (a+4),\] then                                     [RPET 2000]

    A)                 \[\frac{24}{5}\pi \]          

    B)                 \[-2\le a\le 4\]

    C)                 \[-2\le a\le 0\]  

    D)                 \[a\le -2\,\,\text{or}\,\,a\ge 4\]

    Correct Answer: B

    Solution :

               \[\int_{0}^{a}{\,\,x\,dx\le a+4}\]\[\Rightarrow \frac{{{a}^{2}}}{2}\le a+4\]            \[\Rightarrow {{a}^{2}}\le 2a+8\]       \[\Rightarrow {{a}^{2}}-2a-8\le 0\]                                 \[\Rightarrow (a-4)(a+2)\le 0\]\[\Rightarrow -2\le a\le 4\].


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