# How to use the discriminant to find out how many real number roots an equation has for x^2=4?

May 27, 2015

Write your equatiom as:
${x}^{2} - 4 = 0$ which is in the form $a {x}^{2} + b x + c = 0$
Where
$a = 1$
$b = 0$
$c = - 4$
The discriminant $\Delta$ is:
$\Delta = {b}^{2} - 4 a c = = - 4 \left(1 \cdot - 4\right) = 16 > 0$
The fact that $\Delta > 0$ tells you that your equation has 2 Real distinct solutions.

[${x}_{1} = 2$ and ${x}_{2} = - 2$]