Question

If y = 3x^3 - 2x and dx/dt equals 3 , find dy/dt when x = -2. Give only the numerical answer.

Answer 1

Dx/dt=3
y=3x^3-2x
dy/dt=(9x^2)(dx/dt)-2(dx/dt)
When x= -2
dy/dt=(9(-2)^2)(3)-2(3)
=36(3)-6
=102