Posted by **W** on Wednesday, December 14, 2011 at 9:26pm.

If 3x^2-2y^2=4xy + 20, find the point(s) at which the graph from Problem 28 has vertical tangents. I found that dy/dx= (3x-2y)/(2x+2y), but now I don't know what to do. Do I set dy/dx to 0?

- Calculus -
**Reiny**, Wednesday, December 14, 2011 at 11:29pm
For a vertical line, the slope would be undefined, that is,

(3x-2y)/(2x+2y) has to be undefined.

When does that happen?

When the denominator is zero, so

2x + 2y = 0

y = -x

sub into the origianal

3x^2 - 2(-x)^2 = 4x(-x) + 20

5x^2 = 20

x^2=4

x = ±2

if x=2, y = -2,

if x = -2, y = 2

points where tangent is vertical are (2,-2) and (-2,2)

- Calculus -
**W**, Wednesday, December 14, 2011 at 11:32pm
thanks! that was really helpful ;)

## Answer this Question

## Related Questions

- calculus - Find the coordinates of points where the graph of f(x) has horizontal...
- Calculus: Implicit - so i suppose to find slope. i have trouble this problem. my...
- Calculus - The point (1,-2) is on the graph of y^2-x^2+2x=5. Find the value of (...
- calculus - there are two tangents lines to the curve f(x) = 3x^2 that pass ...
- Calculus - How many tangents does the graph of f(x)=(x-1)^2(x-3)^2 have? I found...
- calculus - the line y=x-c touches the ellipse 9x^2 + 16y^2 = 144. Find the value...
- Pre-Calculus - Hello! I'm stuck on how to do this problem and would appreciate ...
- college implicit HELP! - I WANNA KNOW I'M DOING RIGHT. Find the slope of the ...
- MATH/ALGEBRA PLEASE - I am having a real issue with this one problem the problem...
- Calculus - Consider the curve defined by y + cosy = x +1 for 0 =< y =< 2pi...

More Related Questions