2. Sample Papers
  3. NTSE

NTSE Sample Paper NTSE SAT Practice Test-19

  • question_answer
    What is the value of \[{{x}^{3}}+3bx-2a\] If \[x={{(a+\sqrt{{{a}^{2}}+{{b}^{3}}})}^{1/3}}\]\[+{{(a-\sqrt{{{a}^{2}}+{{b}^{3}}})}^{1/3}}\,?\]

    A) \[2{{a}^{2}}\]           

    B) \[-2{{a}^{3}}\]

    C) 1                                 

    D) 0          

    Correct Answer: D

    Solution :

    [d] \[{{x}^{3}}=\left( a+\sqrt{{{a}^{2}}+{{b}^{3}}} \right)+\left( a-\sqrt{{{a}^{2}}+{{b}^{3}}} \right)\] \[+\text{ }3\text{ }\left( {{\text{a}}^{2}}-{{a}^{2}}+{{b}^{3}} \right).\text{ }x\] \[=2a-3b\,\,x\] \[\therefore \,\,{{x}^{3}}+3bx-2a=0\]


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