Question

Find the value of 'a', if $3^5\times 3^a=3^9$

• A. a=3
• B. a=-4
• C. a=4
• D. a=2

Answer 1

The correct option is C a=4

By the Laws of Exponents, we know that $a^m\times a^n=a^{m+n}$
Given $3^5\times 3^a=3^9$
$\Rightarrow$ $3^{5+a}=3^9$ , since the bases are same, equating the exponents gives
$\Rightarrow$ 5+a=9 $\Rightarrow$ a=9-5=4
$\Rightarrow$ a=4