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Chapter: Applications of Derivatives· Mathematics & Statistics (Commerce) Part 1

The cost \(C\) for producing \(x\) articles is given as \(C = x^3 - 16x^2 + 47x\). For what values of \(x\) the average cost is decreasing?Solution : Given \(C = x^3 - 16x^2 + 47x\)Average cost \(C_A = \dfrac{C}{x}\)\(\therefore C_A = \square\)Differ…

Q.3 (C)(i) The cost \(C\) for producing \(x\) articles is given as \(C = x^3 - 16x^2 + 47x\). For what values of \(x\) the average cost is decreasing?

Solution : Given \(C = x^3 - 16x^2 + 47x\)

Average cost \(C_A = \dfrac{C}{x}\)

\(\therefore C_A = \square\)

Differentiating w.r.t. \(x\), we get

\(\dfrac{d}{dx}(C_A) = \square\)

We know that \(C_A\) is decreasing if \(\dfrac{d}{dx}(C_A)\ \square\ 0\)

\(\therefore 2x - 16 \lt 0\)

\(\therefore 2x \lt 16\)

\(\therefore x \lt \square\)

\(\therefore\) Average cost is decreasing for \(x \in (0, 8)\)

1 answer

Best answer

Answer: the boxes are \(x^2 - 16x + 47\); \(2x - 16\); \(\lt\); \(8\).

\(C_A = \dfrac{x^3 - 16x^2 + 47x}{x} = x^2 - 16x + 47\).

\(\dfrac{d}{dx}(C_A) = 2x - 16\).

\(C_A\) is decreasing if \(\dfrac{d}{dx}(C_A) \lt 0\), i.e. \(2x - 16 \lt 0\), i.e. \(x \lt 8\).

Since the number of articles \(x \gt 0\), the average cost is decreasing for \(x \in (0, 8)\).

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