GMAT Problem Solving Question 16: Identities and exponents

 
The following GMAT Problem Solving question tests your understanding of how to recognize algebraic identities and to manipulate exponent terms.

Question 16:

If $8^{2x}+8^{x}=0.75$, then $x=$

1. $\quad -\dfrac{1}{4}$
2. $\quad -\dfrac{1}{3}$
3. $\quad -\dfrac{1}{2}$
4. $\quad -\dfrac{2}{3}$
5. $\quad -\dfrac{3}{4}$