CAIE P3 2021 June — Question 3

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2021
SessionJune
TopicExponential Equations & Modelling

3 The variables \(x\) and \(y\) satisfy the equation \(x = A \left( 3 ^ { - y } \right)\), where \(A\) is a constant.
  1. Explain why the graph of \(y\) against \(\ln x\) is a straight line and state the exact value of the gradient of the line.
    It is given that the line intersects the \(y\)-axis at the point where \(y = 1.3\).
  2. Calculate the value of \(A\), giving your answer correct to 2 decimal places.