x-intercepts exist where y is equal to 0. Where y is equal to 0 is where the graph goes through the x-axis. Our x-intercepts are (2x-3), (x + 3), and (x-4). Again, since x-intercepts exist where y = 0, then by the Zero Product Property, 2x - 3 = 0, x - 4 = 0, and x + 3 = 0. In the first x-intercept:
2x - 3 = 0 and
2x = 3 so
x = 3/2
In the second:
x - 4 = 0 so
x = 4
In the third:
x + 3 = 0 so
x = -3
So the x-intercepts in the correct order are x = 3/2, 4, -3
- The basic formula used in this task is S=V*t, where S - distance, V - speed, t - time.
- the downstream speed is: V+Vc, where V - the speed of the boat in still water, Vc - the speed of the current.
- the upstream speed is: V-Vc.
- according to the described above the distance for downstream is S1=(V+Vc)*t1, where t1=10; the distance for upstream is S2=(V-Vc)*t2, where t2=70.
- for whole travel down- and upstream: S=S1+S2.
- Using these it is possible to make up the system of the equations:
V - the speed of the boat in still water - 6 miles per hour, Vc - the speed of the current - 4.5 miles per hour. All the details for the system of the equations are in the attachment.