Dy/dx=2x+2
So velocity will be zero when 2x+2=0, x=-1
Since d2y/dx2=2, it has a constant positive acceleration of 2, so that when dy/dx=0 it is at an absolute minimum value for f(x), which is also the vertex.
y(-1)=1-2+3=2
So the vertex is at (-1,2), which is an absolute minimum so the parabola opens upwards.
And by symmetry we can say that f(0)=f(-2)=3 so you have another two points that you can see (-2,3) and (0,3)
80 since he starts off with 38 stamps then gains 6 each month for 7 months (6x7=42) so 42+38=80
The answer is 3.1428 (very close to π actually lol)
