Question

If $3\times 3^{k-1}=81$, find value of $k$.

• A. $2$
• B. $3$
• C. $4$
• D. $9$
• E. $27$

Answer 1

The correct option is C $4$

Given, $3\times 3^{k-1}=81$
$\Rightarrow 3^1\times 3^{k-1}=3^4$
$\Rightarrow 3^{k-1+1}=3^4$
$\Rightarrow 3^k=3^4$
$\Rightarrow k=4$ (as the bases are same on both sides)