# Help with curve equation

1. Aug 12, 2010

### jinx007

A curve equation is y = 3x - x^3/2

find the value of X when y=0

2. Aug 12, 2010

### thrill3rnit3

Re: Helpp(urgent)

0 = 3x - x3/2
x3/2 = 3x

tell me if you still need help after that

3. Aug 13, 2010

### jinx007

Re: Helpp(urgent)

Yes infact its there that i am stuck..!!!!!!

4. Aug 13, 2010

### jinx007

Re: Helpp(urgent)

i want to know how to find the value of x

5. Aug 13, 2010

### Staff: Mentor

Re: Helpp(urgent)

x3/2 = 3x

[STRIKE]Hint -- remember that in working with equations, you want to do the SAME thing to both sides of the equation, while working to simplify everything. What operation can you do to both sides of this equation to get rid of an x on both sides....?[/STRIKE]

EDIT -- oops, see better hint later by Mark44

Last edited: Aug 13, 2010
6. Aug 13, 2010

### thrill3rnit3

Re: Helpp(urgent)

Don't forget the case x=0 though.

7. Aug 13, 2010

### Staff: Mentor

Re: Helpp(urgent)

Writing the equation as x3/2 = 3x is NOT a good strategy. Instead, work with x3 - 6x = 0 (equivalent to the one you started with) and factor the cubic expression.

8. Aug 13, 2010

### thrill3rnit3

Re: Helpp(urgent)

They both yield the same answers, except that you lose the solution x=0 if you do the first method. I'm sorry if I forgot to make that clear.

9. Aug 13, 2010

### Staff: Mentor

Re: Helpp(urgent)

That's why factoring is a better strategy - you don't lose solutions.