The equation in the image is:

$x^4 = \underline{\ \ \ } \ \text{when} \ x = 2$

To solve this, we substitute $x = 2$ into the equation $x^4$:

$2^4 = 2 \times 2 \times 2 \times 2 = 16$

Thus, the answer is:

$x^4 = 16 \ \text{when} \ x = 2$

Would you like more details or have any questions?

Here are 5 related questions:

1. What would $x^4$ be when $x = 3$?
2. How do you calculate higher powers of numbers, like $x^5$?
3. What is the general rule for evaluating $x^n$ when $n$ is a positive integer?
4. How does raising a number to a negative power work, e.g., $x^{-4}$?
5. What is the difference between raising a number to an integer power versus a fractional power?

Tip: To quickly evaluate powers of 2, recall the first few values: $2^2 = 4$, $2^3 = 8$, $2^4 = 16$, etc.