Answer:
RPM 1388.889
Horsepower 366.802
Step-by-step explanation:
We do not need to solve the equation for y = 0, which is nice. We can go directly to finding the maximum.
The maximum or minimum of ax^2+bx+c is always at x=-b/2a
with b = 25/45 and a = -1/5000 we get
x = -25/45 / (-2/5000) = 5/9 * 2500 = 12500/9 ≈ 1388.889
Now we only need to put that x into the equation (ideally in form of 12500/9 for accuracy) and we get the horsepower of ~366.802
