0.5 x 4 = 2 feet / 2 feet in 4 seconds
15 - 2 = 13
New depth: 13 feet
0.4 x 3 = 1.2 feet / 1.2 feet in 3 seconds
13 - 1.2 = 11.8
New depth: 11.8 feet
5 times 2/6 is 10/6
You can simplify that to 5/3
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)
Its a line plot, for every number that is listed put a mark above the number on the number line. So if there was 3 6's, on the number line above the 6, put 3 marks like dots or x's to represent the amount of 6.
Hope you understand.