From what you learned aboutfactoring quadraticsandspecial factoring formulas, you know that the above can be restated as:

. . . . .

What result do you get when yousolve the factors?

The Quadratic Formulagives a result (using a = 1, b = 0, and c = -4) that agrees with the "by factoring" result. What formula did you use?

Note: The answer to any "solving" problem can be checked by plugging it back into the original exercise. In your case:

. . . . .