J & K CET Engineering J and K - CET Engineering Solved Paper-2012

  • question_answer
    If the  curve  \[{{x}^{2}}+{{y}^{2}}-2x-2y+1=0\] intersects the coordinate axes at A and B, then equation of straight line joining A and B is         .          

    A)  \[x+y=\sqrt{2}\]

    B)  \[x+y=1\]

    C)  \[x-y=1\]

    D)  \[x-y=\sqrt{2}\]

    Correct Answer: B

    Solution :

    Given curve is \[{{x}^{2}}+{{y}^{2}}-2x-2y+1=0\] Put \[x=0,\] we get \[{{y}^{2}}-2y+1=0\] \[\Rightarrow \] \[{{(y-1)}^{2}}=0\] \[\Rightarrow \] \[y=1\] Now, put \[y=0,\] we get \[{{x}^{2}}-2x+1=0\] \[\Rightarrow \] \[{{(x-1)}^{2}}=0\] \[\Rightarrow \] \[x=1\] Hence, it intersect the coordinate axes at \[A(1,\,0)\] and \[B(0,\,1)\] \[\therefore \] Equation od line passing through \[A(1,\,0)\] and \[B(0,\,1)\] is \[y-0=\frac{1-0}{0-1}\,(x-1)\] \[\Rightarrow \] \[y=\frac{1}{-1}(x-1)\] \[\Rightarrow \] \[x+y=1\]


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