Q. For each, $n \in N$, $10^{2n - 1} + 1$ is divisible by

A) 11
B) 13
C) 9
D) None of these
Explanation

(a)
Let $P(n) = 10^{2n - 1} + 1$
$P(1) = 10 + 1 = 11$
Let $P(k) \equiv 10^{2k - 1} + 1 = 11I\$ is true
Now, $P(k + 1) = 10^{2k + 1} + 1$
$= (11I - 1)100 + 1$
$= 1100I - 99 = 11I_{1}$
So, $P(k + 1)$ is true.

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.