SOLUTION: Please help me. Find the discriminant for the following quadratic equation and use it to determine the number of roots or real solutions it has. x2 + 3x + 15 = 0

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Please help me. Find the discriminant for the following quadratic equation and use it to determine the number of roots or real solutions it has. x2 + 3x + 15 = 0      Log On


   

Question 278853: Please help me.
Find the discriminant for the following quadratic equation and use it to determine the number of roots or real solutions it has.
x2 + 3x + 15 = 0
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B3x%2B15+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%283%29%5E2-4%2A1%2A15=-51.

The discriminant -51 is less than zero. That means that there are no solutions among real numbers.

If you are a student of advanced school algebra and are aware about imaginary numbers, read on.


In the field of imaginary numbers, the square root of -51 is + or - sqrt%28+51%29+=+7.14142842854285.

The solution is

Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B3%2Ax%2B15+%29