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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

Order of Operations with Substitution

Video-Lesson Transcript

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

We all know that it is PEMDAS.

Parenthesis
Exponent
Multiplication
Division
Addition
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.