How do I solve this question? Please explain if possible how the method striked you too.
$$\lim _{x\to 0}\left(\frac{\sqrt{p+x}-\sqrt{p-x}}{\sqrt{q+x}-\sqrt{q-x}}\right)$$
I tried double rationalising the problem, but just ended up with this:
$$\lim _{x\to 0}\left(\frac{\sqrt{q+x}+\sqrt{q-x}}{\sqrt{p+x}+\sqrt{p-x}}\right)$$
I thought of squaring the limit, but that doesn't work too, just ends up with cancelling 2x in the end. I have absolutely no idea on how to proceed. I haven't yet learnt Calculus, just started with Limits.