# Simplifying ExpressionsPage 2

#### WATCH ALL SLIDES

Hint: The idea is that the variable part of the terms must be identical for them to be like terms.

Slide 11

Examples

Like Terms

5x , -14x

-6.7xy , 02xy

The variable factors are

identical.

Unlike Terms

5x , 8y

The variable factors are

not identical.

Slide 12

## Combining Like Terms

Recall the Distributive Property

a (b + c) = b(a) +c(a)

To see how like terms are combined use the

Distributive Property in reverse.

5x + 7x = x (5 + 7)

= x (12)

= 12x

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Example

All that work is not necessary every time.

Simply identify the like terms and add their

coefficients.

4x + 7y – x + 5y = 4x – x + 7y +5y

= 3x + 12y

Slide 14

Slide 15

## Both Skills

This example requires both the Distributive

Property and combining like terms.

5(x – 2) –3(2x – 7)

Distribute the 5 and the –3.

x(5) - 2(5) + 2x(-3) - 7(-3)

5x – 10 – 6x + 21

Combine like terms.

- x+11

Slide 16

Simplifying Example

Slide 17

Simplifying Example

Distribute.

Slide 18

Simplifying Example

Distribute.

Slide 19

Simplifying Example

Distribute.

Combine like terms.

Slide 20

Simplifying Example

Distribute.

Combine like terms.

Slide 21

## Evaluating Expressions

Remember to use correct order of operations.

Evaluate the expression 2x – 3xy +4y when

x = 3 and y = -5.

To find the numerical value of the expression, simply replace the variables in the expression with the appropriate number.

Slide 22

Example

Evaluate 2x–3xy +4y when x = 3 and y = -5.

Substitute in the numbers.

2(3) – 3(3)(-5) + 4(-5)

Use correct order of operations.

6 + 45 – 20

51 – 20

31

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