If `(1+2x+3x^2)^(10)=a_0+a_1x+a_2x^2++a_(20)x^(20),t h e na_1` equals `10` b. `20` c. `210` d. none of these
If `(1+2x+3x^2)^(10)=a_0+a_1x+a_2x^2++a_(20)x^(20),t h e na_1`
equals
`10`
b. `20`
c. `210`
d. none of these
A. 10
B. 20
C. 210
D. none of these
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1 Answers
Correct Answer - B
`a_(1)=` coefficient of `x` in `(1+2n+3x^(2))^(10)`
`=` coefficient of x in `((1+2x)+3x^(2))^(10)`
`=` coefficient of x in `(.^(10)C_(0)(1+2x)^(10) + .^(10)C_(1)(1+2x)^(9)(3x^(2))+"…..")`
`=` coefficient of x in `.^(10)C_(0)(1+2x)^(10)`
`= .^(10)C_(0)2..^(10)C_(1) = 20`
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Answered