Answer
$s(t)=4.9t^2-3t$
Work Step by Step
Here, $a=9.8; v(0)=-3;s(0)=0$
Since the derivative of velocity is acceleration, $v(t)=9.8t+C$
Therefore, $v(0)=-3$ Then $-3=9.8(0)+C \implies C=-3$
Thus, $v(t)=9.8t-3$
Since the derivative of position is velocity, $s(t)=4.9t^2-3t+C'$
Therefore, $s(0)=0$ Then $0=4.9(0)^2-3(0)+C' \implies C'=0$
Hence, $s(t)=4.9t^2-3t$