For each curve Below, find the values of x for which the curve is increasing
i.y=x^2 -4x
ii.y=x^2 -2x-3
iii.y=12+4x-x^2
iv.y=x^3 +3x^2-5
v.y=x^3-6x^2-15x+8
vi.y=24x-3x^2-x^3