Question

If $7^{x-1}+7^{x+1}=\frac{50}{7}$ then find $x$.

• A. $1$
• B. $-1$
• C. $0$
• D. None of these

Answer 1

The correct option is C $0$

$7^{x-1}+7^{x+1}=\frac{50}{7}$

Let $7^x$ be $t$,$t>0$

$\frac{t}{7}+7t=\frac{50}{7}$

$\frac{t+49t}{7}=\frac{50}{7}$

$50t=50$

$\therefore t=1$

$7^x=1$

$x=0$