ExamBro
ExamBro
CUET · MATHS · PYQ PAPER 2025

The length of a rectangle is decreasing at the rate of \(4\) cm / minute and the width is increasing at the rate of \(3\) cm / minute , then the rate of change of the perimeter is

  1. A \(2\) cm / min decreasing
  2. B \(3\) cm / min decreasing
  3. C \(2\) cm / min increasing
  4. D \(3\) cm / min increasing
Verified Solution

Answer & Solution

Correct Answer

(A) \(2\) cm / min decreasing

Step-by-step Solution

Detailed explanation

\(P = 2L + 2W\) \(\frac{dP}{dt} = 2\frac{dL}{dt} + 2\frac{dW}{dt}\) \(\frac{dP}{dt} = 2(-4) + 2(3)\) \(\frac{dP}{dt} = -8 + 6 = -2 \, \text{cm/min}\) The rate of change of the perimeter is \(2 \, \text{cm/min}\) decreasing.