Recent content by cluivee

It must do surely, otherwise it wouldn't intersect all 3 planes?

Homework Statement The plane P1 contains the points A,B,C, which have position vectors a=(0,0,0), b=(1,1,8) and c=(0,1,5) respectively. Plane P2 passes through A and is orthogonal to the line BC, whilst plane P3 passes through B an is orthogonal to the line AC. Find the coordinates of r, the...

I think so, but I need a bit of clarification, I've seen you've used the product rule to get =f(u)+x∂∂xf(u) =f(u)+x∂∂uf(u)∂u∂x. but f(u)= u = y/x right? I know that may be a dumb question. Then d/du(f(u)) = 1 always? And du/dx = -y/x^2? Thanks for your help though Hootenanny

Homework Statement If V=xf(u) and u=y/x, show that x^2.d2V/dx2 + 2xy.d2V/dxdy + y^2.d2V/dy2= 0 (This a partial differentiation problem so all the d's are curly d's) The Attempt at a Solution I have tried to work out d2V/dx2 and the other derivatives, then multiply them by x^2 or 2xy or...