1. ## Parametric equations

A function is defined parametrically by x=5t², y=t^5 + (20t³)/3

a)Find dy/dx in terms of t

b) given that dy/dx=1, show that t³ + 4t - 2=0

Ok for part a i do

dx/dt = 10t

dy/dt= 5t^4 + (180t)/9
=5t^4 + 20t²

dy/dx = (5t^4 + 20t²)/10t
=(t^4 + 4t²)/2t

could anyone confirm this to be right?

also how do i do the next part?

2. Originally Posted by djmccabie
A function is defined parametrically by x=5t², y=t^5 + (20t³)/3

a)Find dy/dx in terms of t

b) given that dy/dx=1, show that t³ + 4t - 2=0

Ok for part a i do

dx/dt = 10t

dy/dt= 5t^4 + (180t)/9
=5t^4 + 20t²

dy/dx = (5t^4 + 20t²)/10t
=(t^4 + 4t²)/2t

could anyone confirm this to be right?

also how do i do the next part?
So far, fine. Of course that is only defined for $t\ne 0$. And you can cancel the t in numerator and denominator to simplify.

To do the second part, set that equal to 1!