Converting rational equations into polynomial equations. A question on my practice exam asks to solve the equation:
$$
\frac{1}{x^4} - \frac{1}{x^2} = 12
$$
In the answers section it says to first convert the equation to the equivalent equation:$$
12x^4 + x^2 - 1 = 0
$$
However, we have not yet learned how to do this and I am unable to contact my teacher before the exam next week. 
So, my question is how does one convert an equation like this into a polynomial like has been achieved in this example?
Any help would be much appreciated!
Jack.

To eliminate all the fractions in a single step, just multiply each term in the equation by the LCM of all the denominators. In this case, $\text{lcm}(x^4, x^2) = x^4$, so we obtain:
\begin{align*}
\frac{1}{x^4} - \frac{1}{x^2} &= 12 \\
x^4 \cdot \frac{1}{x^4} - x^4 \cdot \frac{1}{x^2} &= x^4 \cdot 12 \\
1 - x^2 &= 12x^4 \\
0 &= 12x^4 + x^2 - 1
\end{align*}
