How to Sketch the Curve y^2 = x^3?

  • Thread starter Thread starter aurao2003
  • Start date Start date
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
2 replies · 3K views
aurao2003
Messages
122
Reaction score
0

Homework Statement




Hi everyone, I am not sure how to sketch this:
y^2 = X^3
I have a feeling it will form a parabola.

If I find the square root of both sides I get:
y = X^3/2
Differentiating gives me
dy/dx = 1.5X^1/2. Kind of stuck from here. Please help.

Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
Think about the shape of the graph for y=x2, then y=x3, y=x4 etc. only for values x>0. The shape is roughly the same, no? The only difference is that for x>1 the graph is steeper and for 0<x<1 the graph is lower for larger powers.
So y=x3/2 will be roughly the same as y=x2 for x>0
But remember that when you take the square root of both sides, you need to remember that [tex]\pm[/tex] so your final result of [tex]y^2=x^3[/tex] or [tex]y=\pm x^{3/2}[/tex] is the graph of y=x3/2 for values of x>0 and then exactly the same thing but reflected in the x-axis for y=-x3/2.
 
aurao2003 said:

Homework Statement




Hi everyone, I am not sure how to sketch this:
y^2 = X^3
I have a feeling it will form a parabola.

If I find the square root of both sides I get:
y = X^3/2
Actually, it's
[tex]y = \pm x^{3/2}[/tex]
There are two branches.
aurao2003 said:
Differentiating gives me
dy/dx = 1.5X^1/2. Kind of stuck from here. Please help.
The derivative also has two branches.
[tex]dy/dx = \pm 1.5x^{1/2}[/tex]
aurao2003 said:

Homework Equations





The Attempt at a Solution