JCECE Engineering JCECE Engineering Solved Paper-2015

  • question_answer
    Let \[A\] and \[B\] be two sets defined as given below: \[A=\{(x,\,\,y):|x-3|\,\,<1\,\,and|y-3|<1\}\] \[B=\{(x,\,\,y):4{{x}^{2}}+9{{y}^{2}}-32x-54y+109\le 0\}\] Then,

    A) \[A\subset B\]

    B) \[B\subset A\]

    C) \[A=B\]

    D)   None of these

    Correct Answer: A

    Solution :

    We have, \[|x-3|<1\]and\[|y-3|<1\] \[\Rightarrow \]               \[2<x<4\]and\[2<y<4\] Thus, \[A\] is the set of all points \[(x,\,\,y)\] lying inside the square formed by the lines\[x=2,\,\,x=4,\,\,y=2\] and\[y=4\]. Now,                 \[4{{x}^{2}}+9{{y}^{2}}-32x-54y+109\le 0\] \[\Rightarrow \]               \[4({{x}^{2}}-8x)+9({{y}^{2}}-6y)+109\le 0\] \[\Rightarrow \]               \[4{{(x-4)}^{2}}+9{{(y-3)}^{2}}\le 36\] \[\Rightarrow \]               \[\frac{{{(x-4)}^{2}}}{{{3}^{2}}}+\frac{{{(y-3)}^{2}}}{{{2}^{2}}}\le 1\] Thus, \[B\] is the set of all points lying inside the ellipse having its centre at \[(4,\,\,3)\] and of lengths major and minor axes are 3 and 2 units. It can be easily seen by drawing the graphs of two regions that\[A\subset B\].


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