Question 5273
Solve:
 x^4 - 10x^2 + 25 = 0  This can be factored into:
(x^2 - 5)(x^2 - 5) = 0 Apply the zero products principle:
x^2 - 5 = 0; x^2 = 5; so x = +-sqrt(5)

So you really get four roots:
 Two of them are: {{{x = sqrt(5)}}} and the other two are: {{{x= -sqrt(5)}}}