We want to simplify the expression \( x^{\frac{2}{3}} + \frac{1}{x^{\frac{2}{3}}} \).
This expression can also be thought of as a single fraction:
\[ x^{\frac{2}{3}} + \frac{1}{x^{\frac{2}{3}}} = \frac{x^{\frac{2}{3}} \cdot x^{\frac{2}{3}} + 1}{x^{\frac{2}{3}}} \]
This gives us:
\[ = \frac{x^{\frac{4}{3}} + 1}{x^{\frac{2}{3}}} \]
Now, let's analyze the options provided:
A. \( \frac{x^{\frac{2}{3}} + 1}{x^{\frac{2}{3}}} \) - This does not match our expression.
B. \( \frac{x^{\frac{4}{9}} + 1}{x^{\frac{2}{3}}} \) - The exponent on x is incorrect.
C. \( 1 \) - This does not simplify the expression we have.
D. \( \frac{x + 1}{x^{\frac{2}{3}}} \) - This is also incorrect as the numerator does not equal \( x^{\frac{4}{3}} + 1 \).
E. \( \frac{x^{\frac{4}{3}} + 1}{x^{\frac{2}{3}}} \) - This matches our simplified expression exactly.
Thus, the correct option is:
E. \( \frac{x^{\frac{4}{3}} + 1}{x^{\frac{2}{3}}} \).