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? :-)
It's strange, I don't know this rule. Sorry to keep you, but could you just lay out the whole "multiply both sides by the lowest order denominator" in a more general way so I can remember it?
So: if I have 2 denominators with variables of different exponents, I multiply the entire LHS and the entire RHS by this value, and then simplify. Is that it?