Friday

October 24, 2014

October 24, 2014

Posted by **Jin** on Monday, September 25, 2006 at 5:14pm.

2x(y^3) + (x^2)(y')(3y^2) = 0

And I simplified the answer to

y'= (-2y)/(3x)

so it would be...

[(-2y')(3x)-(-2y)(3)]/(9x^2) and it's simplified to (-6xy'+6y)/(9x^2)= y''

I could plug in (-2y)/(3x) in place of y'.

The correct answer is y''=(10y)/(9x^2), but I did not get this answer. Please help me!

This looks correct, but you dropped the y'

2x(y^3) + (x^2)(y')(3y^2)y' = 0 so

y'=-2x(y^3)/(x^2)(3y^2)=-2y/3x

If we now differentiate this again we get

y"=[3x*(-2y')-(-2y)*3]/(9x^2)=(-6xy'+6y)/(9x^2)

If we now substitute -2y/3x for y' we get

y"=[(-6x*-2y/3x)+6y]/9x^2=[4y+6y]/9x^2

Yes, you should make the substitution for y' and you'll get the correct answer in terms of x and y only.

**Answer this Question**

**Related Questions**

Calculus - How would I go about finding the derivative of f(x)=ln(x)(7x-2)^3 ...

Calculus (Help) - Also I would like to know how to set this problem up in ...

Calculus - R=M^2(c/2-m/3) dR/dM=CM-M^2 I found the derivative. Now how would I ...

Calculus--> bobpursley - How do you get m=0? from taking the second ...

Calc-please help! - What is the second derivative of (x^3)/(x^2-1)? And how ...

Derivatives- Math - Can someone explain how to find the derivative of : 1. y= 5...

calculus - Find the first and second derivative - simplify your answer. y=x/4x+1...

Calculus - derivatives - Okay, I want to find the derivative of (x^x)^(x^x)... ...

Calculus - I need help with finding first and second derivative--simplify your ...

Calculus - I need to find the second derivative of y=x(x-1)^1/2. I found the ...