U4.L3.HW: Logarithmic Properties: Question 19

Question

Answer the blank line. Explain afterwards.

If log_b(7) = 1.8 and log_b(2) = 0.6, then log_b(28) = _____.

Answer 1

28 = 7•2•2

So log_b28 = log_b(7•2•2) = log_b7 + log_b2 + log_b2 = 1.8 + 0.6 + 0.6 = 3.0

Answer 2

log_b(28) = log_b(7x2x2) You can expand the log, multiplication expands to addition.

log_b(7x2x2) =log_b(7) + log_b(2) + log_b(2) = 1.8+.6+.6 = 3.0