Thread: Find normal and where it intersects

1. Find normal and where it intersects

The line that is normal to the curve x^2+xy-2y^2=0 at (5,5) intersects the curve at what other point?

2. Originally Posted by smartartbug
The line that is normal to the curve x^2+xy-2y^2=0 at (5,5) intersects the curve at what other point?
The equation of the normal is y - 5 = m(x - 5) where m is the value of dy/dx at (5, 5). Find m. Then solve simultaneously:

x^2 + xy - 2y^2 = 0 .... (1)

y - 5 = m(x - 5) .... (2)

If you need more help, please show all your working and say where you get stuck.