Question

What are the exact solutions of x2 + 5x + 1 = 0?

Answer 1

I've already told you in another question that you need to make use of the Quadratic Formula.

Answer 2

I don't know how to use it -.-

Answer 3

Keren, Keren... You must get it. If you are tasked with finding exact solutions to quadratic equations, you MUST have been exposed to the Quadratic Formula - well, unless you were sleeping in class, or something.

It can be developed by applying "Completing the Square" to an arbitrary Quadratic Equation.

It is just this:

Given a Quadratic Equation: \(a\cdot x^{2} + b\cdot x + c = 0\), both solutions, Real or Complex, are described by \(x = \dfrac{-b\pm\sqrt{b^{2}-4ac}}{2a}\).

That's it. In your case, you have a = 1, b = 5, and c = 1.

1) You must see where I got those.
2) You must substitute into the Quadratic Formula and simplify.

Now GO! Let's see it.

Answer 4

It's B