Help finding an equation for the level curve

  • Thread starter Thread starter SigmaCrisis
  • Start date Start date
  • Tags Tags
    Curve
AI Thread Summary
To find the equation for the level curve of the function f(x, y) = (x^2 + y^2)e^(xy) that contains the point P(1,0), first evaluate the function at that point to determine the constant k. The level curve is then defined by setting the function equal to this constant, f(x, y) = k. It's important to avoid setting the function to zero, as this leads to incorrect calculations. Using polar coordinates may also simplify the process. Clarifying these steps can help resolve confusion in finding the correct level curve equation.
SigmaCrisis
Messages
15
Reaction score
0
Hey guys, I tried it out, but I just don't get it. I have to find the equation for the level curve f(x, y)=(x^2 + y^2)e^(xy); that contains the point P(1,0). By the way, e^(xy) is read e to the x times y, just in case.


What I did, which looks wrong the whole way was:

(x^2 + y^2)e^(xy) ---> (x^2)(e^(xy)) + (y^2)(e^(xy)) = 0

---> ln(x^2) + ln(e^(xy)) = (-1) ln(y^2) + ln(e^(xy))
---> 2ln(x) + xy = (-1) (2ln(y) + xy)
---> 2ln(x) = (-1)(2ln(y))


...and I'm stuck there. Could anyone help correct this, or if possible, help continue? Thanks a bunch.Help finding an equation for the level curve...

--------------------------------------------------------------------------------

Hey guys, I tried it out, but I just don't get it. I have to find the equation for the level curve f(x, y)=(x^2 + y^2)e^(xy); that contains the point P(1,0). By the way, e^(xy) is read e to the x times y, just in case.


What I did, which looks wrong the whole way was:

(x^2 + y^2)e^(xy) ---> (x^2)(e^(xy)) + (y^2)(e^(xy)) = 0

---> ln(x^2) + ln(e^(xy)) = (-1) ln(y^2) + ln(e^(xy))
---> 2ln(x) + xy = (-1) (2ln(y) + xy)
---> 2ln(x) = (-1)(2ln(y))


...and I'm stuck there. Could anyone help correct this, or if possible, help continue? Thanks a bunch.
 
Physics news on Phys.org
sorry bout the double pasting there.
 
I believe that level curves are values of f(x,y) where f(x,y) = a constant.

To find the level curve of f(x, y)=(x^2 + y^2)*e^(x*y) that contains the point p(1,0):

Step 1: Evaluate f(x,y) at p(1,0) that is, f(1,0) = constant k

Step 2: your level curve that contains the point p(1,0) is then just
f(x,y) = k, the constant you found in step one.

I hope this helps, if not, let me know and I'll work an example similar to the one you posted above.

Best Regards,

Edwin
 
Why don't you use polar coordinates? Also, why are you setting the function to 0? You should be setting it to f(1, 0) -- as edwin suggested!
 
Thanks a bunch guys...
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
I was thinking using 2 purple mattress samples, and taping them together, I do want other ideas though, the main guidelines are; Must have a volume LESS than 1600 cubic centimeters, and CAN'T exceed 25 cm in ANY direction. Must be LESS than 1 kg. NO parachutes. NO glue or Tape can touch the egg. MUST be able to take egg out in less than 1 minute. Grade A large eggs will be used.
Back
Top