A) 2
B) 3
C) 4
D) 7
Correct Answer: B
Solution :
Given, \[^{{{a}^{2}}-a}{{C}_{2}}{{=}^{{{a}^{2}}-a}}{{C}_{4}}\] \[\Rightarrow \] \[^{{{a}^{2}}-a}{{C}_{2}}{{=}^{{{a}^{2}}-a}}{{C}_{{{a}^{2}}-a-4}}\]\[[{{\because }^{n}}{{C}_{r}}{{=}^{n}}{{C}_{n-r}}]\] \[\Rightarrow \] \[{{a}^{2}}-a-4=2\] \[\Rightarrow \] \[{{a}^{2}}-a-6=0\] \[\Rightarrow \] \[(a-3)(a+2)=0\] \[\Rightarrow \] \[a=3\]or \[-2\]You need to login to perform this action.
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