Solve the Equation $$5 ^ { 2 x } - 3 \left( 5 ^ { x } \right) = 40$$

Multiple Choice

Solve the equation. Give the answer in exact form.
- $$5 ^ { 2 x } - 3 \left( 5 ^ { x } \right) = 40$$

A) $\left\{ \log _ { 5 } 8 , \log _ { 5 } ( - 5 ) \right\}$
B) $\left\{ \log _ { 5 } 8 \right\}$
C) $\{ 5 \ln 8,5 \ln ( - 5 ) \}$
D) $\{ 5 \ln 8 \}$