Monday 9/22

1. Monday 9/22 • Block 2 Integers In Class p.49 Lesson 2.3 Subtracting Integers Examples 1-3 Homework p.50 Exercises 1-26

2. Warm-Up < > 1 – 14 0 –30 Complete each statement with < or >. • −9 −2 • −80 −81 Find the value of each expression. • −9 + 10 • −6 + (−8) • −2 + 2 • −5 + (−15) + (−10)

3. Lesson 2.3 Subtracting Integers Subtract two integers to find the difference.

4. Good to Know! When subtracting integers, one method is to make the expression into an addition expression by adding the opposite. Example – 8 – 2 = ? Add the Opposite 1. Change the subtraction to addition. 2. Change the sign of the number after the subtraction sign.  If this number is positive, make it negative.  If it is negative, make it positive. 3. Add. (–2) – 8 + = –10

5. Subtracting Integers • Subtract the integers by adding the opposite. • Follow the rules for adding integers to determine the sum.

6. Example 1 Use a number line to find the value of –2 – 3. –2 – 3 is –2 + (–3) Add the opposite and use the number line to find the value. –2 – 3 = –5 –2 + (–3) = –5

7. Example 2 Use integer chips to find the value of –5 – (– 4). Subtract the integers by adding the opposite: –5 + 4 –5 – (– 4) = –1 = + –5 4 –1

8. Example 3 The melting point of mercury is approximately –39º C. The melting point of chlorine is approximately –101º C. How much higher is mercury’s melting point than chlorine’s melting point? Write the problem. –39 – (–101) Add the opposite. –39 + 101 Find the sign of the larger 101 – 39 = 62 absolute value and subtract. Mercury’s melting point is 62º C higher than chlorine’s melting point.

9. Monday 9/22 • Block 2 Integers In Class p.49 Lesson 2.3 Subtracting Integers Examples 1-3 Homework p.50 Exercises 1-26

10. Exit Problems Find the value of each expression. • 20 − (−8) • −11 + 7 • −6 − 2 • 100 + (−45) • 30 − 39 • 22 − (−2) 28 –4 –8 55 –9 24

11. Communication Prompt How is subtracting integers similar to adding integers?