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Cbray
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Homework Statement
Find the rate of change of the area of a square whose side is 8 cm long, if the side length is increasing at 2cm/min
Homework Equations
A(t) = xy
x(0)=8
y(0)=8
dx/dt=2
dy/dt=2
The Attempt at a Solution
dA/dt = dx/dt * x * dy/dt * y
Using the product rule...
dA/dt = dx/dt * x * y + dy/dt * y * x
What happens now? Does the dx/dt * x = 1?
or is it..
dA/dt = dx/dt * d/dx * x * dy/dt * d/dy * y
Using the product rule..
dA/dt = dx/dt * d/dx * x * y + dy/dt * d/dy * y * x
Therefore the d/dx = 1, therefore..
dA/dt = dx/dt * y + dy/dt * x
dA/dt = 2*8 + 2*8
dA/dt = 32 cm^2/min ?? If it is correct is what I'm thinking correct (ie my working?)Help, thanks!
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