Use properties of logarithms to find the exact value of the expression

Question

log_7 (343 * 7^15)

Answer 1

log₇ (343*7^15)
= log₇ 343 + log₇ 7^15
= log₇ 7^3 + 15log₇7
= 3log₇7 + 15log₇7
= 3(1) + 15(1)
= 18