## ahamed Group Title A body moves along a horizontal line according to s=f(t)=t^3-9t^2+24t a) when is s increasing and when it is decreasing? b) when v is increasing and when it is decreasing? one year ago one year ago

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1. richyw

$\frac{ds}{dt} = 3t^2-18t+24$$\frac{d^2s}{dt^2} = 6t-18$ a) when $$\frac{ds}{dt}>0$$, s is increasing, when $$\frac{ds}{dt}<0$$, s is decreasing b) when $$\frac{d^2s}{dt^2}>0$$, v is increasing, when $$\frac{d^2s}{dt^2}>0$$, v is decreasing

2. richyw

oops the last statement in b should have a < sign (just like in a)