Question 6
LogarithmsSolve: log3 x + log3 (x − 8) = 2.
- A.6
- B.7
- C.8
- D.9
Show the answer and explanation
Answer: D (9)
Explanation
log3[x(x − 8)] = 2 gives x² − 8x = 9, so (x − 9)(x + 1) = 0. Logs need x > 8, so x = 9.
Solve: log3 x + log3 (x − 8) = 2.
Answer: D (9)
log3[x(x − 8)] = 2 gives x² − 8x = 9, so (x − 9)(x + 1) = 0. Logs need x > 8, so x = 9.