For the first one, you need to use Implicit Differentiation. You can start by reshaping the equation so it reads

When you differentiate both sides, you should get

Again, you can reorder this one more time so you have

At this point, plug in the point you're given so you get

Now you can find the equation for the line using the slope and point you have.

For the second problem, just use Differentiation to get

Try this one on your own. I will help you if you need it.