WMA12/01 Oct 2024, Question 6: Solving Exponential and Log Equations
Pearson Edexcel International AS Level Mathematics · Pure Mathematics 2 (WMA12) · Calculator · 5 marks
The question, in short
Solve log base 4 of (12 − 2x) equals 2 plus twice log base 4 of (x + 1) using logarithm laws, showing full working without relying on calculator methods.
Summarised in our own words. Use the official paper for the exact wording and any diagrams.
Solution · 5 marks
- 12log₄(x + 1) = log₄(x + 1)²
- 2log₄(12 − 2x) − log₄(x + 1)² = 2, so log₄[(12 − 2x)/(x + 1)²] = 2
- 3(12 − 2x)/(x + 1)² = 4² = 16
- 412 − 2x = 16x² + 32x + 16, so 8x² + 17x + 2 = 0
- 5(8x + 1)(x + 2) = 0, so x = −1/8 or x = −2
- 6x = −2 makes x + 1 negative, so reject it: x = −1/8
Answerx = −1/8
Stuck on a step? Read the free lesson: Solving Exponential and Log Equations
Practise more solving exponential and log equations questions
Real XMA01 past-paper questions, marked on your working like the exam, with a worked solution for every part.
Practise free on LemmaraMore past-paper questions on solving exponential and log equations
Also searched as: WMA12 October 2024 · WMA12/01 · wma12 oct24 · IAS Maths Pure Mathematics 2 October 2024 · question 6.
Lemmara is an independent study tool, not affiliated with or endorsed by Pearson Edexcel. The worked solutions are Lemmara’s own.