1.

The sum of rational term(s) in `(sqrt3 + 2^(1/3) + 5^(1/4))^8` is equal toA. 3150B. 336C. 3486D. 3592

Answer» Correct Answer - d
The general term in the expansion of
`(sqrt(3) + root(3)(2)+ root(4)(5))^(8)` is
`(8!)/(r!s!t!)(3)^(r//2) (2)^(s//3)(5)^(1//4)`, where ` r + s + t = 8`
For rational terms, we must have,
`(i) r = 3 , s=6, t=0 " "(b) r = 4 , s = 0, t= 4`
`(c) r = 0 , s=0, t=8 " "(d) r = 8 , s = 0, t= 0`
`therefore ` Sum of rational terms
`(8!)/(3!6!0!)xx3xx2^(2)xx5^(0) + (8!)/(4!0!4!)xx3^(2)xx2^(0)xx5`
`(8!)/(0!0!8!)xx3^(0)xx2^(0)xx5^(2) + (8!)/(8!0!0!)xx3^(4)xx2^(0)xx5^(0)`
= 3592


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