# How do you use the Change of Base Formula and a calculator to evaluate the logarithm #log_5 7#?

##### 3 Answers

#### Explanation:

The change of base formula says that:

In this case, I will switch the base from

Plugging this into a calculator, we get:

#### Explanation:

**The Change of Base Formula :**

#### Explanation:

#"the "color(blue)"change of base formula"# is.

#â€¢color(white)(x)log_b x=(log_c x)/(log_c b)#

#"log to base 10 just log and log to base e just ln"#

#"are both available on a calculator so either will"#

#"give the result"#

#rArrlog_5 7=(log7)/(log5)~~1.21" to 2 dec. places"#

#"you should check using ln"#