Solve the equation In 3 + ln(2x + 5) = 2ln(x + 2). Give your answer in a simplified exact form.
- Solve the equation In 3 + ln(2x + 5) = 2ln(x + 2). Give your answer in a simplified exact form.[4]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2020). The mark or mark type is shown in brackets.
- [M1] Use law of logarithm of a power and sum and remove logarithms
- [A1] Obtain a correct equation in any form, e.g. 3(2x+5)=(x+2)²
- [M1] Use correct method to solve a 3-term quadratic, obtaining at least one root
- [A1] Obtain final answer x = 1+2√3 or 1 + √12 only
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