## wcaprar 3 years ago Find the second derivative of the parametric equation.

1. wcaprar

Parametric Equation: x=9t, y=6t-8 I got dy/dx = $4/((1/2)t ^{-1/2})$ Now I need to find d^2y/dx^2. And I got $-t ^{-3/2}/((1/2)t ^{-1/2})^3$ But It says that I got it wrong. Where did I go wrong?

2. dumbcow

wouldn't dy/dx = 2/3 $\frac{dy}{dx} = \frac{dy}{dt}*\frac{dt}{dx} = 6*\frac{1}{9} = \frac{2}{3}$

3. campbell_st

I would have used substitution t = x/9 then y = 6(x/9) - 8 dy/dx = 2/3 then 2nd derivative d^y/dx^2 = 0

4. SmoothMath

How did you get: dy/dx = 4/((1/2)t−1/2)?