First slide

Binomial theorem for positive integral Index

Question

The remainder when $7^{128}$ is divided by 10 is

Moderate

A

1
B

3
C

7
D

9

Solution

$\begin{array}{l} 7^{128} - {(7^{2})}^{64} - (50 - 1)^{64} - (1 - 50)^{64} \\ = 1 + \sum_{k = 1}^{64}^{64} C_{k} (- 50)^{k} \end{array}$
Thus, remainder when $7^{128}$ is divided by 10 is 1.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App