Solve u² = 49, where u is a real number.
Simplify your answer as much as possible.

Step-by-step explanation:

To undo the square on the u, you have to take the square root of both sides:

The square root of u-squared is just u, so that's easy.  When you take the square root of 49, however, you have to remember that what you get is both the positive and the negative of the square root of 49 which is 7.  This is because 7 squared is 49 and so is (-7) squared.  So the answer is

u = ±7

25% is the answer