Question

In the expansion of $\frac{e^{7x} + e^{3x}}{e^{5x}}$ , the constant term is.

• A. 0
• B. 1
• C. 2
• D. None of these

Answer 1

Answer: (C)

2

Answer 2

$1 + \frac{4^{2}}{3!} + \frac{4^{4}}{5!} + ......\infty =$

We know

$\frac{e^{4} + e^{- 4}}{4}$ ......(i)

$\frac{e^{4} - e^{- 4}}{4}$ ......(ii)

Adding (i) and (ii), we get

$\frac{e^{4} + e^{- 4}}{8}$

Hence the constant term is 2.