Edexcel AS Paper 1 2018 June — Question 5

Exam BoardEdexcel
ModuleAS Paper 1 (AS Paper 1)
Year2018
SessionJune
TopicLaws of Logarithms

  1. A student's attempt to solve the equation \(2 \log _ { 2 } x - \log _ { 2 } \sqrt { x } = 3\) is shown below.
$$\begin{aligned} & 2 \log _ { 2 } x - \log _ { 2 } \sqrt { x } = 3
& 2 \log _ { 2 } \left( \frac { x } { \sqrt { x } } \right) = 3
& 2 \log _ { 2 } ( \sqrt { x } ) = 3
& \log _ { 2 } x = 3
& x = 3 ^ { 2 } = 9 \end{aligned}$$ using the subtraction law for logs simplifying using the power law for logs using the definition of a log
  1. Identify two errors made by this student, giving a brief explanation of each.
  2. Write out the correct solution.