Step-by-step explanation:
since the y- axis stands for velocity (and the x-axus for time), speeding up means when the curve goes up (increasing velocity), and slowing down means when the curve goes down (decreasing velocity), all when reading the graph from left to right (small time values to larger time values).
(a)
speeding up
t in [0, 1)
or
0 <= t < 1
I would exclude t = 1, because at that point the slope is 0, there is no speeding up there.
slowing down
t in (1, 3)
or
1 < t < 3
the same argumentation for excluding 1 and 3, because there the slope of the curve turns 0 (just the turning point from one tendency to the other), and there is no speeding up or slowing down at these points.
(b)
speeding up
t in (1. 2)
or
1 < t < 2
slowing down
t in [0, 1) or in (2, infinity)
or
0 <= t < 1 || 2< t < infinity
we could use 3 instead of infinity, as this seems to be the last point of the drawn curve, but normally this kind of drawing tells me "infinity".
