Question

The general term in the series $11,21,31,41,51,...$ will be

• A. $10n-9$
• B. $10n-1$
• C. $n+10$
• D. $10n+1$

Answer 1

The correct option is D

$10n+1$

Explanation for correct option :

Option D : By putting $n=1,2,3,4,5...$ in $10n+1$, we get

When $n=1,$then the general term $10n+1=10\times 1+1=11$

When $n=2,$ then the general term $10n+1=10\times 2+1=21$

When $n=3,$then the general term $10n+1=10\times 3+1=31$

When $n=4,$then the general term $10n+1=10\times 4+1=41$

…….

Therefore, $10n+1$ is the general term of series.

Explanation for incorrect options :

Option A : If we put $n=1,2,3,4,5...$ in $10n-9$ , we get series $1,11,21,31....$

So, which is not true.

Option B : If we put $n=1,2,3,4,5...$ in $10n-1$ , we get series $9,19,29,39,.....$

So, which is not true.

Option C : If we put $n=1,2,3,4,5...$ in $n+10$ , we get series $11,12,13,14,....$

So, which is not true.

Hence, the option D is the correct answer.