January 26, 2015

Homework Help: Calculus

Posted by Anonymous on Thursday, May 15, 2008 at 5:02pm.

If x = t^2 + 1 and y = t^3, then d^2y/dx^2 =

I know I can solve for t in terms of x and substitute that into y = t^3 and find the double derivative.

I also know that I can take the derivative of x and y then divide dy/dt by dx/dt. Then take the derivative to get the answer.

However, my question is why can't you find d^2x/dt^2 and d^2y/dt^2 and divide to find d^2y/dx^2?

x = t^2 + 1
dx/dt = 2t(dt/dt) + 0(dt/dt)
d^2x/dt^2 = 2(dt/dt) = 2

y = t^3
dy/dt = 3t^2(dt/dt)
d^2y/dt^2 = 6t(dt/dt)

d^2y/dx^2 = (d^2y/dt^2)/(d^2x/dt^2)
d^2y/dx^2 = 6t / 2 = 3t

The correct answer, however, is 3/4t. Why? Am I doing something wrong -.-?

Answer this Question

First Name:
School Subject:

Related Questions

ALGEBRA 1!PLZ HELP! - Use the Substitution method to solve the system of ...
Pre-Calculus - If you solve the following system of equations by substitution, ...
algebra - 5x-2y=-5 y-5x=3 substitution Substitute 5x +3 for y in the first ...
Algebra22222!!! - Choose the ordered pair that is a solution to the system of ...
algebra - use substitution to solve the linear system 3x+2y=-5 4x-3y=16 help plz...
algebra - use substitution to solve the linear system 3x-y=15 x+2y=-2 Solve for ...
Math - Find the Maximum area for the given perimeter of a rectangle. State the ...
math,help!!!! - How do i do thois problem?Please help. Problem #1 solve the ...
Math - I just don't understand this question: h(t)=A*b^x h(3)=4 h(5)=40 Solve ...
Algebra 1 - What is an equation of a line perpendicular to the line with ...