Solve the equation 8³⁻⁶ˣ = 4×5⁻²ˣ. Give your answer correct to 3 decimal places.
- Solve the equation 8³⁻⁶ˣ = 4×5⁻²ˣ. Give your answer correct to 3 decimal places.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.
- [B1] Use law of the logarithm of product or quotient on each side
- [DB1] Use law of logarithm of a power involving x on ONE side, e.g. ln 8³ + (-)6x ln 8 or (3 – 6x) ln 8 or (9-18x) ln2 or ln 4-2xln 5
- [B1] Obtain a correct linear equation in x, e.g. (3-6x)ln8 = (9-18x) In2 = ln 4-2x ln 5
- [B1] Obtain answer x = 0.524
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