Answer:
DA/dt = 75.27 cm²
Step-by-step explanation:
Cube Volume = V(c) = 683 cm³
DV(c) /dt = 824 cm³
V(c,x) = x³
Then
DV(c,x)/ dt = 3x² Dx/dt
( DV(c,x)/ dt )/ 3x² = Dx/dt (1)
Now as V(c,x) = x³ when V(c,x) = 683 cm³ x = ∛683
x = 8.806 ( from excel)
And by subtitution of this value in equation (1)
Dx/dt = ( DV(c,x)/ dt )/ 3x² ⇒ Dx/dt = 824 / 3*x²
Dx/dt = 824 /3*77.55
Dx/dt = 824/232,64
Dx/dt = 3,542
Then we got Dx/dt where x is cube edge. The area of the face is x² then
the rate of change of the suface area is
DA/dt = ( Dx/dt )²*6 ( 6 faces of a cube)
DA/dt = (3.542)²*6
DA/dt = 75.27 cm²
Answer is A
Hope it helps
The maximum number of microwave ovens the two employees can take on the elevator is 7.
<h3>How to find the maximum number of microwave ovens the two employees can take on the elevator?</h3>
To solve the question, we have to find the simple equation showing the relationship between all the weights an the maximum weight the elevator can carry
Let
- x = number of microwave ovens
Since the micro wave weighs 45 pounds, the total weight of microwave ovens is W = 45x.
Also, there are 20 televisions on the elevator. If each television weighs 85 pounds, the total weight of televisions is W' = 20 × 85 = 1700 pounds
Also, the weight of the equipment and the two employees is W" = 400 pounds.
Since the maximum weight on the elevator is 2400 pounds, we have that the required simple equation is
W + W' + W" = 2400
45x + 1700 + 400 = 2400
45x + 2100 = 2400
45x = 2400 - 2100
45x = 300
x = 300/45
x = 6.67
x ≅ 7
So, the maximum number of microwave ovens the two employees can take on the elevator is 7.
Learn more about simple equation here:
brainly.com/question/26184005
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