SOLUTION: Find the x values at which the following parabolas cross the x-axis. a) y= x^2 + 5x + 4 b) y= x^2 + 4x + 5

Question 191250: Find the x values at which the following parabolas cross the x-axis.
a) y= x^2 + 5x + 4
b) y= x^2 + 4x + 5
Answer by Mathtut(3670) (Show Source): You can put this solution on YOUR website!
set y=0
:
a)
:
x=-4 and -1 (-4,0), (-1,0)
:
b)
:

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

The discriminant -4 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 -4 is + or - .

The solution is , or
Here's your graph:

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