Question

The number $a_n=6^n-5n$ for $n=1,2,3,....$ when divided by $25$ leave the remainder

• A. $9$
• B. $7$
• C. $3$
• D. $1$

Answer 1

The correct option is D $1$

Given that,

$an=6^n-5n$

For $n=1,2,3,\mathrm{4.......}$

thus, $a_1=6^1-5\times 1=1$

$a_2=6^2-5\times 2=26$

$a_3=6^3-5\times 3=501$

$a_4=.....$

when divided by $25$

then, the reminder $=1$