Amy Hall

Evaluating an expression

Evaluating an expression is basic algebra that can be explained very easily.

A basic problem has letters in it instead of numbers.

This makes it look quite confusing.

All you have to do is plug the numbers in for the letters and

solve the problem like a numerical expression.         It is IMPORTANT to remember the famous

PEMDAS.

This explains the order of operations in which the problem should be worked.

An easy way to remember that is

"Please Excuse My Dear Aunt Sally."

P stands for parentheses

E stands for exponents

M stands for multiplication

D stands for division

A stands for addition

S stands for subtraction    All you have to do is follow this order while working a problem!

Example 1:

If a = 4 and b = 5, what is ab – 2b?

Since there are no parentheses or exponents,

you first plus in the values for a and b and multiply those together.

(4 ´ 5) You get 20.

Then, you multiply 2b or (2 ´  5 )which gives you 10.

Last, you subtract the second answer from the first (20 -10),

which gives you 10!

Example 2:

Evaluate 6x / 4 when x = 6.

Because multiplication and division are equal in the order of operations, you solve the problem by reading it from left to right like one would read a book.

6 x 6 = 36.

You then divide that number by 4.

The correct answer is 9.

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