David W. answered • 08/25/16

Tutor

New to Wyzant
The precedence rules ("order of operations") does follow

**P-E-M-D-A-S**("Please Excuse My Dear Aunt Sally") as follows: 1] Parenthesis

2] Exponentiation

3] Multiplication or Division (left-to-right)

4] Addition or Subtraction (left-to-right)

Extra notes:

Re-apply P-E-M-D-A-S within Parenthesis if it is a complex expression.

Re-start each scan after performing any replacement.

Some expressions assume multiplication, so (a+b)(c+d) means (a+b)*(c+d).

A unary "+" or "-" [no value preceding it] assumes that 0 is included, so "-a-b" means "(0-a)-b" [one unary, one subtract], not "-(a-b), which is (0-a)+b and also equals (-1)*(a-b)"

In the expression, "9 - (3x2) +8." something is subtracted from 9, not subtract 9 from something.