Question

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

Answer 1

`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`