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VITEEE 2015 Paper

Section: Mathematics

Question : 106 of 120

Marks: +1, -0

Solution:

Surface area A of a cube of side x is givenby A =

6x^2

On differentiating w.r.t. x, we get

\frac{dA}{dx}

= 12x

Let the change in x be Ax = m% of x

\frac{mx}{100}

Change in surface area,

ΔA =

\left(\frac{dA}{dx}\right)

Δx = (12x) Δx

= 12 x

\left(\frac{3x}{100}\right)

\frac{12x^2m}{100}

∴ The approximate change in surface area

\frac{2m}{100} \times 6x^2

= 2m% of original surface area

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