JEE Main & Advanced Sample Paper JEE Main - Mock Test - 45

  • question_answer
    Total number of integral values of 'a' so that \[{{x}^{2}}-\left( a+1 \right)x+a-1=0\] has integral roots, is equal to:

    A) 2                     

    B)        1

    C) 4                     

    D)        None of these

    Correct Answer: B

    Solution :

    [b] \[{{x}^{2}}-ax-x+a-1=0\] \[{{x}^{2}}-ax-x+a=1\] \[\underset{\operatorname{int}eger}{\mathop{\underset{\downarrow }{\mathop{\left( x-a \right)}}\,}}\,\underset{\operatorname{int}eger}{\mathop{\underset{\downarrow }{\mathop{\left( x\text{ }-\text{ }1 \right)}}\,}}\,=\underset{\operatorname{int}eger}{\mathop{\underset{\downarrow }{\mathop{1}}\,}}\,\]       \[x,a\text{ }\in \text{ }integer\] only possible if \[\Rightarrow \] \[\] is only single a for which it is possible


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