The following is my working:

[/FONT] dL/dt = 12 cm/min

dW/dt = 4 cm/min

dH/dt = 2 cm/min

V = L x W x H

we get:

V=(200+12t)(50+4t)(30+3t)

\(\displaystyle V = 144t^3 + 5460t^2 + 72000t + 300,000\)

Derivative of V

\(\displaystyle V' = 432t^2 + 10920t + 72000\)

Now, I'm very confused. How could we find the rates of change,when [FONT="]200 cm in length, 50 cm in width and 30 cm in height?

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Thanks!

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