Question

How do you solve `|9x - 90| = 0`?

Answer 1

Only solution is `x=10`

Explanation:

Note that if `|x=0|`, it is either `x=0` or `-x=0`. Bot mean `x=0`

Similarly `|9x-90|=0` means that absolute value of `9x-90` is zero,

it means either `9x-90=0` or `-(9x-90)=0`

i.e. either `9x=90` or `-9x+90=0`

i.e. either `x=90/9=10` or `-9x=-90` and `x=(-90)/(-9)=10`

Hence the only solution is `x=10`