How do you solve #log x + log 3 = log 21#?

1 Answer
Dec 18, 2015

#color(white)(xx)=>x=7#

Explanation:

#color(white)(xx)logx+log3=log21#

The sum of the logarithms is the logarithm of a product of the numbers being added:

#color(white)(xx)color(red)(log(3x))=log21#
#=>color(red)(1/3xx)3x=color(red)(1/3xx)21#
#=>x=7#