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## Homework Statement

At t=0 the current to a dc electric motor is reversed, resulting in an angular displacement of the motor shaft given by theta (t) = ( A)t-( B)t^{2}-( C)t^{3}

At what time is the angular velocity of the motor shaft zero?

## Homework Equations

quadratic

## The Attempt at a Solution

I continue to be very confused by this question. I thought all I need to do was take the derivative with respect to time and then plug those coefficients into the quadratic equation.

So I get:

(2B(+/-)((4B^2+12AC)^.5))/2A