Answer:
Part 1) The engine speed that maximizes torque is [tex]3,093 rev/min[/tex]
Part 2)The maximum torque is [tex]74.683\ foot-pounds[/tex]
Step-by-step explanation:
The correct equation is
[tex]y=-3.75x^{2}+23.2x+38.8[/tex]
This is the equation of a vertical parabola open downward (because the leading coefficient is negative)
The vertex represent a maximum
The x-coordinate of the vertex represent the engine speed that maximizes torque
The y-coordinate of the vertex represent the maximum torque
Solve the quadratic equation by graphing
using a graphing tool
The vertex is the point (3.093,74.683)
see the attached figure
therefore
The engine speed that maximizes torque is
[tex]3.093(1,000)=3,093 rev/min[/tex] ---> because is in thousands of revolutions per minute
The maximum torque is
[tex]74.683\ foot-pounds[/tex]