1. if y= x(x^2 + 4) find dy/dx
2. then find the equation of the tangent to the curve where x=1 giving answer in the form y=mx+c
3. the normal to the curve y=x^3 + ax at coordinates (2,b) has gradient 1/2. find the values of the constants a and b.
1. dy/dx = 3x^2 + 4
2. I assume we would use y-y1 = m(m-m1) where the 1 is at the bottom of the y and m, but we only have one coordinate, which is x=1. So I am not sure about this
3. I haven't got a clue what the 'normal to the curve is'