Write an integer for each situation Get out

Write an integer for each situation. Get out homework and a red pen. 1. stock market down 56 points Label Journals 2. a score of 3 3. a bank deposit of $25 Evaluate each expression. 3 -2 & 3 -3: Add & Subtract Integers Complete the quick check to the left 4. 5. 6. What is the value of Course 2, Lesson 3 -2 if k = − 6 and m = − 2

ANSWERS 1. − 56 2. 3 3. 25 4. 19 5. 14 6. 4 Course 2, Lesson 3 -2

Homework and red pen Clear everything else. We will check hw now. Course 2, Lesson 3 -1

Course 2, Lesson 3 -1

Course 2, Lesson 3 -1

The Number System WHAT happens when you add, subtract, multiply, and divide integers? Course 2, Lesson 3 -2

The Number System • I can… • Add and subtract integers. • Solve real world problems involving integers Course 2, Lesson 3 -2

The Number System • Opposites: numbers that are the same distance from zero (Example: 2 and -2) • additive inverse: another way of saying opposite. When we add opposites, they equal zero. Course 2, Lesson 3 -2

The Number System Add Integers with the Same Sign Words To add integers with the same sign, add their absolute values(the number parts without signs). Keep the sign the same. The sum is: • positive if both integers are positive. • negative if both integers are negative. Examples Course 2, Lesson 3 -2 7 + 4 = 11 − 7 + (− 4) = − 11

Adding Integers with the same sign: – 3 + (– 2). Course 2, Lesson 3 -1 – 6 + (– 3) – 26 + (– 17).

The Number System Add Integers with Different Signs Words To add integers with the different signs, subtract their absolute values(the number parts without signs). The sum will have the same sign as the larger absolute value(number part). . The sum is: • positive if the positive integer’s absolute value is greater. • negative if the negative integer’s absolute value is greater. Examples Course 2, Lesson 3 -2 9 + (− 4) = 5 − 9 + 4 = − 5

Adding Integers with different signs 5 + (– 3). Course 2, Lesson 3 -1 8 + (– 7). 7 + (– 7).

Step-by-Step Example Find 2 + (– 15) + (– 2) Same problem 2 ways 2 + (– 15) + (– 2)

Need Another Example? Find 11 + (– 4) + (– 11).

Step-by-Step Example 8. A roller coaster starts at point A. It goes up 20 feet, down 32 feet, and then up 16 feet to point B. Write an addition sentence to find the height at point B in relation to point A. Then find the sum and explain its meaning. Need Another Example?

The Number System Subtract Integers Words To subtract an integer, don’t subtract at all. Change the problem to addition by adding the opposite (keep, change). Once you change it to addition, follow addition rules. Symbols 7 – 15 becomes 7 + (-15) which equals -8 Examples 4 − 9 = 4 + (− 9) = − 5 Course 2, Lesson 3 -3 7 − (− 10) = 7 +(10) = 17

Step-by-Step Example 8 – 13 2 – 15 – 10 – 7 Need Another Example?

Step-by-Step Example Evaluate x – y if x = – 6 and y = – 5. Need Another Example?

Need Another Example? Evaluate g – h if g = – 2 and h = – 7.

Need Another Example? In Mongolia, the temperature can fall to – 45° Celsius in January. The temperature in July may reach 40° Celsius. Find the difference between these two temperatures in Mongolia. Answer 85°C

The Number System How did what you learned today help you answer the WHAT happens when you add, subtract, multiply, and divide integers? Course 2, Lesson 3 -2

The Number System How did what you learned today help you answer the WHAT happens when you add, subtract, multiply, and divide integers? Sample answers: • The sum of two positive integers is positive. • The sum of two negative integers is negative. • To find the sum of two integers with different signs, subtract their absolute values and use the sign of the integer with the greater value. • When you subtract an integer, you add its additive inverse.

Homework: • Page 207 # 4 -13 all • AND • Page 219 # 7 -12 and 14 -17 Course 2, Lesson 3 -1