A) 120
B) 210
C) 240
D) 480
Correct Answer: A
Solution :
\[{{T}_{r+1}}\,{{=}^{10}}{{C}_{r}}.\,{{x}^{5r}}\,;\,\,r=0,\,\,1,\,\,2,....,\,10\] \[\therefore \] For coefficient of \[{{x}^{35}},\] put \[5r=35\] \[\therefore \,r=7\] So, \[{{T}_{8}}\,{{=}^{10}}{{C}_{7}}\,{{x}^{35}}\Rightarrow \,\] Coefficient of \[{{x}^{35}}={{\,}^{10}}{{C}_{7}}\,=\frac{10!}{7!.3!}=\frac{10\times 9\times 8}{6}\,=120\]
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