1.

The coefficient of `a^8b^4c^9d^9`in `(a b c+a b d+a c d d+b c d)^(10)`is`10 !`b. `(10 !)/(8!4!9!9!)`c. `2520`d. none of theseA. `10!`B. `(10!)/(8!4!9!9!)`C. `2520`D. none of these

Answer» Correct Answer - C
`a^(10)b^(10)c^(10)d^(10)(1/a+1/b+1/c+1/d)^(10)`
Therefore the required coefficient is equal to the coefficient of
`a^(-2)b^(-6)c^(-1)d^(-1)` in `(1/a+1/b+1/c+1/d)^(10)`, which is given by
`= (10!)/(2!6!1!1!) = (10 xx 9 xx 8 xx 7)/(2) = 2520`


Discussion

No Comment Found

Related InterviewSolutions