The coefficient of the middle term in the binomial expansion in powers of `x` of`(1+alphax)^4` and of`(1-alphax)^6` is the same, if `alpha` equals
The coefficient of the middle term in the binomial expansion in powers
of `x`
of`(1+alphax)^4`
and of`(1-alphax)^6`
is the same, if `alpha`
equals
A. `-5/3`
B. `10/3`
C. `-3/10`
D. `3/5`
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1 Answers
Correct Answer - C
Middle term of `(1+alphax)^(4)` is `T_(3)`.
Its coefficient is `.^(4)C_(2)(alpha)^(2)=6alpha^(2)`.
Middle term of `(1-alphax)^(6)` is `T_(4)`.
Its coefficient is `.^(6)C_(3) (-alpha)^(3) = -20alpha^(3)`.
According to question.
`6alpha^(2) = - 20 alpha^(3)`
or `3alpha^(2)+ 10alpha^(3) = 0`
or `alpha^(2) (3+10alpha) = 0`
or `alpha = -3/10`
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