Originally Posted by

**yorkey** Here I've got a sum that I have to reorder into a quadratic equation so I can find the two roots of it, but I'm struggling to understand how. Once into the quadratic form, I can easily find the roots, but the problem for me is getting it into the quadratic form.

18/x^4 + 1/x^2 = 4

Now what I did was put the x^4 on the other side. So it's:

x^4 - x^-2 - 18 = 0

Is this right?

According to the mark scheme, I had to add the two fractions together, but I don't see why that is the right option. Any help? :-)