Given: Log2=a, Log7=b. Find: Log 56.

Question

I don't know how to solve this. Can someone help me? How do I use the information above to help me find Log 56?

Simpler exercises: find out $\log(2^3)$ and $\log(8\times 7)$. — , Nov 27 '18 at 01:21

score 3 · Accepted Answer · edited Nov 27 '18 at 03:46

3

$\log(56) = \log(7\cdot8) = \log(7) + \log(8) = \log(7) + \log\left(2^{3}\right) = \log(7) + 3\log(2) = b + 3a$

edited Nov 27 '18 at 03:46

Andrew Li

answered Nov 27 '18 at 01:25

ZAF

I got the answer correct. I think you made a mistake, because the computer said the answer is 3a+b. Thanks for the help though ZAF. – THE CONFUSED PERSON Nov 27 '18 at 01:27
Might I suggest "\cdot" ($\cdot$) instead of a period to indicate multiplication. – Doug M Nov 27 '18 at 01:28
Corrected, thanks! – ZAF Nov 27 '18 at 01:30

score 2 · Answer 2 · answered Nov 27 '18 at 01:27

2

Hint 1: $56= 7\cdot 2^3$

Hint 2: $\log (x\cdot y^z)= \log x+ z\log y$

answered Nov 27 '18 at 01:27

MPW

2 Answers2