Hi guys

I've been doing some revision for my yearlies and I'm stuck on these questions:

1) Find the values of m for which the curves y = mx and y = abs(sinx) have only one common point.

2) Show that, if the line y = mx + c is a tangent to the curve 4x^2 + 3y^2 = 12, then c^2 = 3m^2 + 4.

3) The curves with equations y = 4/x + 2 and y = ax^2 + bx + c have the following properties:

1. there is a common point where x = 2

2. there is a common tangent where x =2

3. both curves pass through the point (1,6)

Find the values of a, b and c.

Could you please help me out?

Thanx a lot.