KVPY Sample Paper KVPY Stream-SX Model Paper-17

  • question_answer
    The area of the region bounded by the curves \[y=\left| x-1 \right|\] and \[y=3-\left| x \right|\] is

    A) 6 sq. units

    B) 2 sq. units

    C) 9 sq. units

    D) 4 sq. units.

    Correct Answer: D

    Solution :

    \[A=\int\limits_{-1}^{0}{\left\{ \left( 3+x \right)-\left( -x+1 \right) \right\}dx+}\]\[\int\limits_{0}^{1}{\left\{ \left( 3-x \right)-\left( -x+1 \right) \right\}dx+}\]\[\int\limits_{1}^{2}{\left\{ \left( 3-x \right)-\left( x-1 \right) \right\}dx}\]
    \[=\int\limits_{-1}^{0}{\left( 2+2x \right)dx+\int\limits_{0}^{1}{2dx+\int\limits_{1}^{2}{\left( 4-2x \right)dx}}}\]
    \[=[2x-{{x}^{2}}]_{-1}^{0}+[2x]_{\,\,\,0}^{1}+{{[4x-{{x}^{2}}]}_{1}}^{2}\]
    \[=0-\left( -2+1 \right)+\left( 2-0 \right)+\left( 8-4 \right)-\left( 4-1 \right)\]
    \[=1+2+4-3=4sq.units\]


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