Showing all necessary working, solve the equation (3^(2x) + 3^(-x)) / (3^(2x) - 3^(-x)) = 4. Give your answer correct to 3 decimal places.
- Showing all necessary working, solve the equation (3^(2x) + 3^(-x)) / (3^(2x) - 3^(-x)) = 4. Give your answer correct to 3 decimal places.[4]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.
- [M1] Reduce the equation to a horizontal equation in 3^(3x), 3^(3x+1) or 27^x
- [A1] Simplify and reach 3(3^(3x)) = 5, 3(27^x) = 5, or equivalent
- [M1] Use correct method for finding x from a positive value of 3^(3x), 3^(3x+1) or 27^x
- [A1] Obtain answer x = 0.155
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