JEE Main & Advanced Sample Paper JEE Main Sample Paper-1

  • question_answer
    The number of real solutions of the equation \[{{2}^{x/2}}+{{(\sqrt{2}+1)}^{x}}={{(5+2\sqrt{2})}^{x/2}}\] is

    A)  1                                            

    B)  2

    C)  4                                            

    D)  infinite

    Correct Answer: B

    Solution :

    \[{{2}^{x/2}}+{{(\sqrt{2}+1)}^{x}}={{(5+2\sqrt{2})}^{x/2}}\] \[\therefore \]\[{{\left( \frac{\sqrt{2}}{\sqrt{5+2\sqrt{2}}} \right)}^{x}}+{{\left( \frac{\sqrt{2}+1}{\sqrt{5+2\sqrt{2}}} \right)}^{x}}=1\] Let\[\cos x=\frac{\sqrt{2}}{\sqrt{5+2\sqrt{2}},}\]then\[\sin x=\frac{\sqrt{2}+1}{\sqrt{5+2\sqrt{2}}}\] \[\therefore \]\[{{\cos }^{x}}\alpha +{{\sin }^{x}}\alpha =1\]\[\Rightarrow \]\[z=2\]


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