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# How do you evaluate log 10 4+log 10 25?

### 7 Answers

- 1 decade agoFavorite Answer
a property of logarithms states that

logb ac = logb a + logb c

therefore

log10 4 + log10 25 = log10 (4*25)

=log10 (100)

=2

- Richard SLv 61 decade ago
Logs are exponents. When you add exponents you are multiplying. So finding the answer to "log4 + log25" means you are multiplying "4 x 25" Since we know that 4 x 25 = 100 - and, since you are dealing in Base 10 logs, the answer to "log4 + log25" should be 2 because Log 10 100 = 2.

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- Anonymous1 decade ago
Well, this is the same thing as:

log[10](100), because the laws of logarithms state that if you have:

log[b]a+log[b]c (b being the same base), you can multiply a and c together, to have:

log[b](ac)

Now, this is an easy logarithm to figure out.

10 to the power of what equals 100? Well let's put this into an equation really quick:

10^x=100

We can easily see that x=2 therefore the answer is 2.

Have a nice day now!! :-)

Source(s): Grade 10 Math