Order Of Operations With Substitution

In this video, we will be learning how to use the order of operations (PEMDAS) in word problems involving substitution.

For example:

$3x + 4y^2 - 8z$

Let $x = 5, y = -2, z=3$

Substitute first into parenthesis:   $3(5) + 4(-2)^2 - 8(3)$

Evaluate the exponent:                   $3(5) + 4(4) - 8(3)$

Multiply:                                             $15 + 16 - 24$

Addition/Subtraction:                      $31 - 24$

Simplify:                                              $7$

Video-Lesson Transcript

Let’s go over the order of operations with substitution.

We all know that it is PEMDAS.

Parenthesis
Exponent
Multiplication
Division
Subtraction

For example:

$3x + 4y^2 - 8z$
Let $x = 5$, $y = {-2}$, and $z = 3$

In order to evaluate this, we have to substitute these values using parenthesis.

$3(5) + 4{(-2)^2} - 8(3)$

Let’s solve the exponent part first.

$3(5) + 4(4) - 8(3)$

Then, let’s multiply.

$15 + 16 - 24$

Now, our answer is $7$.

So the key is to substitute using parenthesis. Then follow the rules in PEMDAS.