Solve log equation with domain restrictions

Solve logarithmic equation where domain constraints eliminate one or more algebraic solutions.

7 questions · Standard +0.2

1.06f Laws of logarithms: addition, subtraction, power rules
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Edexcel Paper 2 2023 June Q3
5 marks Moderate -0.3
  1. Given that
$$\log _ { 2 } ( x + 3 ) + \log _ { 2 } ( x + 10 ) = 2 + 2 \log _ { 2 } x$$
  1. show that $$3 x ^ { 2 } - 13 x - 30 = 0$$
    1. Write down the roots of the equation $$3 x ^ { 2 } - 13 x - 30 = 0$$
    2. Hence state which of the roots in part (b)(i) is not a solution of $$\log _ { 2 } ( x + 3 ) + \log _ { 2 } ( x + 10 ) = 2 + 2 \log _ { 2 } x$$ giving a reason for your answer.
Edexcel Paper 2 2020 October Q3
5 marks Moderate -0.3
  1. (a) Given that
$$2 \log ( 4 - x ) = \log ( x + 8 )$$ show that $$x ^ { 2 } - 9 x + 8 = 0$$ (b) (i) Write down the roots of the equation $$x ^ { 2 } - 9 x + 8 = 0$$ (ii) State which of the roots in (b)(i) is not a solution of $$2 \log ( 4 - x ) = \log ( x + 8 )$$ giving a reason for your answer.
AQA Paper 1 2023 June Q6
5 marks Standard +0.8
6 Show that the equation $$\begin{aligned} & \qquad 2 \log _ { 10 } x = \log _ { 10 } 4 + \log _ { 10 } ( x + 8 ) \\ & \text { has exactly one solution. } \\ & \text { Fully justify your answer. } \end{aligned}$$
Edexcel C2 Q4
6 marks Standard +0.3
Solve $$2 \log_3 x - \log_3 (x - 2) = 2, \quad x > 2.$$ [6]
AQA AS Paper 2 2023 June Q4
5 marks Moderate -0.3
Find the exact solution of the equation \(\ln(x + 1) + \ln(x - 1) = \ln 15 - 2\ln 7\) Fully justify your answer. [5 marks]
SPS SPS FM 2026 November Q6
5 marks Standard +0.3
Find the values of \(x\) such that $$2\log_3 x - \log_3(x - 2) = 2$$ [5]
Pre-U Pre-U 9794/2 2010 June Q2
5 marks Standard +0.8
Solve the inequality $$\log_3(2x^2 - x) - \log_3(2x^2 - 3x + 1) > 1.$$ [5]