Answer: D. 12 ft
Step-by-step explanation:
Answer:
The rate at which the distance between the two cars is increasing is 30 mi/h
Step-by-step explanation:
Given;
speed of the first car, v₁ = 24 mi/h
speed of the second car, v₂ = 18 mi/h
Two hours later, the position of the cars is calculated as;
position of the first car, d₁ = 24 mi/h x 2 h = 48 mi
position of the second car, d₂ = 18 mi/h x 2 h = 36 mi
The displacement of the two car is calculated as;
displacement, d² = 48² + 36²
d² = 3600
d = √3600
d = 60 mi
The rate at which this displacement is changing = (60 mi) / (2h)
= 30 mi/h
We can create two equations here:
(1) Volume = area of square * height of box
85.75 = s^2 h
(2) Cost = 3 * area of square + 1.5 * area of side box
C = 3 s^2 + 1.5 s h
From (1), we get:
h = 85.75 / s^2
Combining this with (2):
C = 3 s^2 + 1.5 s (85.75 / s^2)
C = 3 s^2 + 128.625 s-
Taking the 1st derivative and equating dC/ds =
0:
dC/ds = 6s – 128.625 / s^2 = 0
Multiply all by s^2:
6s^3 – 128.625 = 0
6s^3 = 128.625
s = 2.78 cm
So h is:
h = 85.75 / s^2 = 85.75 / (2.78)^2
h = 11.10 cm
So the dimensions are 2.78 cm x 2.78 cm x 11.10 cm
The total cost now is:
C = 3 (2.78)^2 + 1.5 (2.78) (11.10)
C = $69.47
Answer:
<6 OR b>-3
Step-by-step explanation:
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