# How do I solve this expression?

I have the following expression:
6a/(2x+8)3+a

My problem is that I don't know if I should solve it as :
6a                                6a
_____________    or     _______________ * 3+a
(2x+8)3+a                      (2x+8)

How am I supposed to know which one is correct?
Math / Science

Last Comment
ThomasMcA2
Dan Craciun

Operator precedence. /* comes before +-

HTH,
Dan
aburr

THIS SOLUTION IS ONLY AVAILABLE TO MEMBERS.
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
NevSoFly

your right there is no way to know with just the straight text.  Thx!
ThomasMcA2

There is a way to know "with just the straight text" because every math expression has an order of operations that defines the order that each sub-expression gets processed.

Because of those "ordering rules" your example gets processed like this:
``````    6a
__________ + a
(2x+8)3
``````
NevSoFly

ThomasMcA2,

could you please explain to me exactly how you came up with the expression that you did given the order of operations?
ThomasMcA2

In the United States the acronym PEMDAS is a common mnemonic to help remember the order. It stands for Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.

Following that order for your problem { 6a/(2x+8)3+a }, the parentheses must be evaluated first. Since there is nothing inside the parentheses that can be simplified, the "times 3" that is outside the parentheses comes next, which simplifies to this: { 6a/(6x+24)+a }.
NevSoFly

I see where I started to go wrong.  After I couldn't simply what was in the Parentheses I restarted at the beginning of the expression, basically I did PEDMAS instead of PEMDAS.  But how do you determine if it should be :
6a                                6a
_____________    or     _______________ +a
(6x+24)+a                      (6x+24)
ThomasMcA2

Because addition and subtraction are always last. So when you do the multiplication and division first, you get "something plus 'a'."

In other words, trying to change the problem to "6a over something" is merely adding to the confusion. If you do it in-line, you get this: { 6a/(6x+24)+a } which clearly does not have "+a" in the divisor.
Math / Science

The Math / Science topic primarily includes discussions of mathematics, physics, statistics and economic analysis, but also biology, chemistry and other sciences.

10K
Questions
--
Followers
--
Top Experts
Get a personalized solution from industry experts

TRUSTED BY