Question

The coefficient of middle term in the expansion of $|b| < |a|$ is.

• A. $\frac{1}{\sqrt{5 + 4x}}$
• B. $x < 1$
• C. $|x| < 1$
• D. None of these

Answer 1

Answer: (B)

$x < 1$

Answer 2

Here, index = 10, an even number, therefore, middle term is $15C_{4}2^{4}$ i.e. 6^th term.

Also,$15C_{8}2^{8}$⇒Coefficient of middle term $\left( x^{2} - \frac{1}{x} \right)^{9}$