AQA C2 2008 January — Question 8

Exam BoardAQA
ModuleC2 (Core Mathematics 2)
Year2008
SessionJanuary
TopicExponential Functions

8
  1. Sketch the graph of \(y = 3 ^ { x }\), stating the coordinates of the point where the graph crosses the \(y\)-axis.
  2. Describe a single geometrical transformation that maps the graph of \(y = 3 ^ { x }\) :
    1. onto the graph of \(y = 3 ^ { 2 x }\);
    2. onto the graph of \(y = 3 ^ { x + 1 }\).
    1. Using the substitution \(Y = 3 ^ { x }\), show that the equation $$9 ^ { x } - 3 ^ { x + 1 } + 2 = 0$$ can be written as $$( Y - 1 ) ( Y - 2 ) = 0$$
    2. Hence show that the equation \(9 ^ { x } - 3 ^ { x + 1 } + 2 = 0\) has a solution \(x = 0\) and, by using logarithms, find the other solution, giving your answer to four decimal places.
      (4 marks)