## anonymous one year ago Will give a medal. Need help urgently. Which of the following is a solution of x^2 + 5x = -2?

1. anonymous

2. P0sitr0n

$\frac{-5\pm\sqrt{17}}{2}$ by solving it using the quadratic formula

3. anonymous

Can you explain it completely so that I know how to do it in the future?

4. P0sitr0n

Recall that is $\frac{-b\pm\sqrt{b^2-4ac}}{2a}$, where a is the coefficient of x^2 (1 in our case), b is of x (5 in our case) and c is the constant term (2 in our case, dont forget the total experssion must be = 0)

5. P0sitr0n

This will give you two roots, (note the plus / minus)

6. anonymous

ok.. then you just solve right @P0sitr0n ?

7. P0sitr0n

yep

8. P0sitr0n

this formula was derived specifically for this purpose

9. P0sitr0n

that said, don't forget to always check that the term under the square root (called the dicriminant) is always positive or zero

10. P0sitr0n

basically you only plug in a, b and c into the formula (those coefficients are taken from your equation)