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NTSE Sample Paper NTSE SAT Practice Test-9

  • question_answer
    If \[xy=6\]and \[x+{{x}^{2}}y+x{{y}^{2}}+y=63\], then \[{{x}^{2}}+{{y}^{2}}\] is equal to                 

    A) 23                                

    B) 55

    C) 69   

    D) 81

    Correct Answer: C

    Solution :

    [c] \[x+{{x}^{2}}y+x{{y}^{2}}+y=63\] \[\Rightarrow \,(x+y)(1+xy)=63\] \[\Rightarrow \,(x+y)(1+6)=63\,\,or\,\,x+y=9\] \[\therefore \,\,{{x}^{2}}+{{y}^{2}}={{(x+y)}^{2}}-2xy=81-2\times 6=69.\] :. x2 + v2 - (x + yY ~- 2.XV - 81 - 2 x 6 == 69.                        


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