A) (28, 315)
B) (-54, 315)
C) (-21, 714)
D) (24, 861)
Correct Answer: A
Solution :
Coefiicient of \[{{x}^{2}}={}^{15}{{C}_{2}}\times 9-3a\left( {}^{15}{{C}_{1}} \right)+b=0\] \[\Rightarrow -45a+b+{}^{15}{{C}_{2}}\times 9=0\] ....(i) Also, \[-27\times {}^{15}{{C}_{3}}+9a\times {}^{15}{{C}_{2}}-3b\times {}^{15}{{C}_{1}}=0\] \[\Rightarrow 9\times {}^{15}{{C}_{2}}\,a-45\,b-27\times {}^{15}{{C}_{3}}=0\] \[\Rightarrow 21\,a-\,b-273=0\] ?(ii) ...(ii) + (ii) \[24a+672=0\]\[~\Rightarrow a=28\] So, \[b=315\]You need to login to perform this action.
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