The side of a square is measured to be 12 ft with a possible error of ±0.1 ft. use differentials to estimate the error in the calculated area. include units in your answer

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The side of a square is measured to be 12 ft with a possible error of ±0.1 ft. Use differentials to estimate the error in the calculated area. Include units in your answer?.
✔️X is the side
✔️A is the area of square. 
✔️dA=d(X^2)=2X*dxThe error on A would be 
✔️delta(A)=2*X*delta(X) = 2*10*0.1 (ft^2)=2 ft^2 
✔️Then the error is +-2 ft^2

Hoped This Helped, Cello10
Your Welcome :) 

The answer would be -3.9> -4.5