11th Class Mathematics Sample Paper Mathematics Olympiad - Sample Paper-8

  • question_answer
    Root of the equation- \[{{\mathbf{3}}^{\mathbf{x-1}}}\mathbf{+}{{\mathbf{3}}^{\mathbf{1-x}}}\mathbf{=2}\]

    A)  \[x=0\]                        

    B)  \[x=1\]        

    C)  \[x=2\]                        

    D)  \[x=-1\]

    Correct Answer: B

    Solution :

    [b] \[\therefore {{3}^{x-}}^{1}+{{3}^{1-x}}=2\] \[\Rightarrow \frac{3x}{3}+\frac{3}{{{3}^{x}}}=2\] Let \[{{3}^{x}}=y\] \[\frac{y}{3}+\frac{3}{x}=2\] \[\Rightarrow {{y}^{2}}-6y+9=0\] \[{{(y-3)}^{2}}=0\] \[\Rightarrow y=3,3.\] Hence, \[{{3}^{x}}=y=3\] \[\Rightarrow x=1\]


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