Question

If y = 3x3 – 2x and dx, dt equals 3, find dy, dt when x = –2. Give only the numerical answer. For example, if dy, dt = 4, type only 4.

Answer 1

y=3x^3-2x, dx/dy =3

dy/dt= ? (when x=-2)

dy/dt= d/dt (3x^3 -2x)

      = 9x^2(dx/dt) -2(dx/dt)

      = 9(-2)^2 * 3 - (2*3)

      = 9(4)*3 -6

      = 102