We are asked to differentiate \( x^2 \) with respect to \( x^3 \), so we need to use the chain rule. \[ \frac{d}{dx} \left( \frac{x^2}{x^3} \right) = \frac{d}{dx} \left( x^{2 - 3} \right) = \frac{d}{dx} \left( x^{-1} \right) \] \[ \frac{d}{dx} \left( x^{-1} \right) = -x^{-2} = \frac{2}{3x} \]
Step 2: Verify the options
The correct derivative is \( \frac{2}{3x} \), matching option (A).
A store has been selling calculators at Rs. 350 each. A market survey indicates that a reduction in price (\( p \)) of calculators increases the number of units (\( x \)) sold. The relation between the price and quantity sold is given by the demand function:
\[ p = 450 - \frac{x}{2}. \]
Based on the above information, answer the following questions:

A ladder of fixed length \( h \) is to be placed along the wall such that it is free to move along the height of the wall.
Based upon the above information, answer the following questions:
(iii) (b) If the foot of the ladder, whose length is 5 m, is being pulled towards the wall such that the rate of decrease of distance \( y \) is \( 2 \, \text{m/s} \), then at what rate is the height on the wall \( x \) increasing when the foot of the ladder is 3 m away from the wall?