Answer:
Step-by-step explanation:
a). 
= 
= 
= 
[Since, i = 
]
b). 
= 
= 
= 5 ± 2i [Since, i = ]
c). 
= 
= 
= 
= 
[Since, i = ]
We have the following function that is a
quadratic function:
So the graph of this function is shown in the figure below. This is a <em>parabola</em> as you can see. The roots of this functions, that is, the x-intercepts are:
As you can see in the figure. This function decreases from
and increases from
Finally, another thing we can see from the graph is that the vertex is the point:
Plane #1 speed: x mph
Plane #2 speed: (x+30) mph
time = time becomes
170 mi 185 mi
---------- = --------------
x x+30
Solving for x, the speed of the slower plane, we get
170x + 5100 = 185 x
5100
Then 15x = 5100, and x = ---------- (mi/hr) = 340 mph
15
The slower plane flies at 340 mph, and the faster one at 370 mph.
