You are Here: Home

# What is the formula for parametric second derivatives? watch

1. Lost a notebook containing the formula and can't remember it to save my life..
zazy
xxxx
2. dy/dx = dy/dt dt/dx = (dy/dt)/(dx/dt)

d²y/dx² = d/dx (dy/dx)

= dt/dx d/dt(dy/dx)

= dt/dx d/dt[(dy/dt)/(dx/dt)]
= dt/dx [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)²

= [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)³

(i hope thats right, im doing it on the fly)
3. (Original post by elpaw)
dy/dx = dy/dt dt/dx = (dy/dt)/(dx/dt)

d²y/dx² = d/dx (dy/dx)

= dt/dx d/dt(dy/dx)

= dt/dx d/dt[(dy/dt)/(dx/dt)]
= dt/dx [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)²

= [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)³

(i hope thats right, im doing it on the fly)
As far as i can trace it's correct... you're a lifesaver....I'll strangle my friend...

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 26, 2004
Today on TSR

### Are you living on a tight budget at uni?

From budgets to cutbacks...

### University open days

1. Loughborough University
Fri, 21 Sep '18
2. University of Cambridge
Fri, 21 Sep '18
3. Richmond, The American International University in London