7.Binomial Theorem
normal

Find the coefficient of $x^{49}$ in the expansion of $(2x + 1) (2x + 3) (2x + 5)----- (2x + 99)$

A

${2^{50}} \times 2500$

B

${2^{49}} \times 2500$

C

${-2^{50}} \times 2500$

D

${-2^{49}} \times 2500$

Solution

$(2 n+1)(2 n+3)(2 n+5) \dots(2 x+99)$

$\Rightarrow 2^{50}\left[\left(\mathrm{x}+\frac{1}{2}\right)\left(\mathrm{x}+\frac{3}{2}\right)\left(\mathrm{x}+\frac{5}{2}\right) \ldots\left(\mathrm{x}+\frac{99}{2}\right)\right]$

Coefficient of $\mathrm{x}^{49}$ is equal to $-(\mathrm{sum} \text { of roots })$

$=2^{50}\left[\frac{1}{2}+\frac{3}{2}+\frac{5}{2}+\ldots .+\frac{99}{2}\right]=2^{49} \times 2500$

Standard 11
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.