basically you treat the derivative expressions like fractions, if you recall fraction division you should see a (not very useful but fine if you want to know if they're equivalent, don't write this in exam) proof.
when x=2t, y=4t^2, why is the answer different when you do the1) (dy/dt)/(dx/dt)=8t/2=4t version and when you first make x=2t and y=4t^2 into y=x^2 and differentiate this graph into 2x?
You need to fix the title, it's "parametric equations", not "functions". If you look closely, you'll see that this cannot be a function because different y values are given by the same x value.
