1. 1.2.1 – Algebraic Expressions, PEMDAS

2. You are familiar with equations…right? Algebraic expressions are similar, but no equal signs (not solving for anything) – Combination of variables (letter to represent one or more numbers) and operations (+, -, etc.)

3. PEMDAS We will encounter numerous types of algebraic expressions; some may be used to model real life scenarios or situations – 2x + 9 – 3(p – 7) + 10 Before evaluating them, always must consider the order of operations – Gives us a guide on how to evaluate expressions correctly PEMDAS

4. P = parenthesis – Always start on inner most set; work your way out E = exponents – Always check signs M = multiplication D = division A = addition S = subtraction

5. Typically, after you substitute a value for a variable, most follow the order of operations to obtain the correct answer Example. Evaluate 3(x + 1) – 2 if x = 4 – What do you do with the x = 4 part?

6. Example. Evaluate ((x + 2)/2) + 9 x 2 for x = 5

7. Example. Evaluate -2 ∕2 + 6 x 4 Example. Evaluate 4 – 3(7 + 2)

8. Powers With large scale multiplication, need a quick way to complete it – Multiplication is essentially fast hand addition We use powers for repeated multiplication – Two parts; – Base = factor being multiplied – Exponent = numbers of times multiplied – Example. 7 x 7 x 7 = 7 3

9. With powers, always have to be careful about negative signs and parenthesis (use our knowledge of PEMDAS to help) Example. Evaluate the following expressions A) 2 3 B) (-2) 3 C) -2 3

10. Example. Evaluate the following. A) -16 2 B) 6 3 C) -2 5 D) (-2) 5

11. Not all exponents are the same! Always be aware of the negative sign – It’s like a “-1” – Using multiplication after exponents

12. Example. Evaluate -4p 2 + 4p – 2 if p = 2. Example. Evaluate 2x 2 + 2x – 1 if x = -2.

13. Assignment Pg. 12 15-19 odd, 21-27 odd, 33-39 odd, 48, 50, 54