Problem: If log102=a and log103=b, then log512 equals:
Answer Choices:
A. 1+aa+b
B. 1+a2a+b
C. 1+aa+2b
D. 1−a2a+b
E. 1−aa+2b
Solution:
Let log312=x∴5x=12∴xlog105=log1012
∴x=log105log1012=log1010−log1022log102+log103=1−a2a+b
or
Use the formula logsN=logbN÷logba