You first get the equation in this form with the positive:
then you substitute in this
Then you simplify and you get two answers, one using the + and
one using the -.
Example:
Write it in descending order on the left with only 0 on the right:
Multiply through by -1 to make the first term positive:
Now simplify:
The two solutions are:
and
You can get the approximate decimal values with a calculator:
and
Edwin