1. Evaluating Algebraic Expressions

2. Evaluate Evaluate has the word “valu” hidden inside
When you see the word “evaluate” – you know that your answer is going to be a value.
Let’s try one.
Evaluate 2xy – 3yz if x = 2, y = 5, and z = -3

3. Bird’s nesting
To evaluate this algebraic expression, we’re going to use a technique that I call “bird’s nesting”. It may sound silly but it will save you a world of hurt when it comes to sign mistakes.

4. Evaluate 2xy – 3yz if x = 2, y = 5, and z = -3
I’m going to rewrite the expression, but every time I get to a letter, I’m going to insert an open ( ) instead the proverbial bird’s nest. 2( )( ) – 3( )( )

5. See how the ( ) keeps everything straight!
Let’s meet our little feathered friends!
x = 2, y = 5, and z = -3
2xy – 3yz
And fly them into their nests
2( 2 )( 5 ) – 3( 5 )( -3 )
4( 5 ) -15( -3 ) 65
-3( 5 ) = -15
2( 2 ) = 4
-15( -3 ) = +45
See how the ( ) keeps everything straight!

6. Evaluating Algebraic Expressions
Expect a value for your answer.
Replace all the letters with ( )
Fly the ‘birds’ into their ‘nests’ (be careful to get the right bird into the right nest!).
Follow the order of operations and the rules of signed numbers.