A coat of paint of thickness 0.04 cm is to be applied uniformly to the faces of a cube of edge 28 cm. Use differentials to find the approximate amount of paint (in cm3) required for the job, correct to the nearest cubic centimeter. Hint: The volume of a cube of edge s is V = s3.

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Answer:

The approximate amount of paint required for the job is [tex]94.08 \: cm^3[/tex].

Step-by-step explanation:

Given a function y = f(x) we call dy and dx differentials and the relationship between them is given by,

                                          dy = f′(x)dx

Let s be the edge of the cube.

The volume of a cube is given by

[tex]V=s^3[/tex]

The amount of paint needed is

[tex]\Delta V \approx dV[/tex]

Differentiating, we get:

[tex]dV=3s^2ds[/tex]

When [tex]s=28[/tex] and the thickness is [tex]ds=0.04[/tex], this becomes

[tex]dV=3(28)^2(0.04)\\dV=94.08 \: cm^3[/tex]

The approximate amount of paint required for the job is [tex]94.08 \: cm^3[/tex].

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