An escalator lifts people to the second floor of a building 25 feet above the first floor. The escalator rises at a 30 degree an
gle. How far does a person travel from the bottom to the top of the escalator?
1 answer:
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Answer:
cm
Step-by-step explanation:
The volume of the box is:
V = height * length * width
V = x*(66 - 2*x)*(90 - 2*x)
V = (66*x - 2*x^2)*(90 - 2*x)
V = 5940*x - 132*x^2 - 180*x^2 + 4*x^3
V = 4*x^3 - 312*x^2 + 5940*x
where x is the length of the sides of the squares, in cm.
The mathematical problem is :
Maximize: V = 4*x^3 - 312*x^2 + 5940*x
subject to:
x > 0
2*x < 66 <=> x < 33
In the maximum, the first derivative of V, dV/dx, is equal to zero
dV/dx = 12*x^2 - 624*x + 5940
From quadratic formula
But , then is not the correct answer.