Question 374363
The fastest way to answer this question uses the discriminant, {{{b^2 - 4ac}}}, with the a, b and c coming from {{{ax^2+bx+c}}}. If this expression is:<ul><li>zero, then there is one real solution.</li><li>positive, then there are two real solutions</li><li>negative, then there are two complex (non-real) solutions</li></ul>
For {{{x^2-4}}} the discriminant is:
{{{(0)^2-4(1)(-4)}}}
which simplifies as follows:
0 - 4(1)(-4)
0 + 16
16
This is positive so there are two real solutions.