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Chapter 1 Review of Real Numbers 2

1.5 Adding Real Numbers

Adding two numbers with the same sign Add their absolute values. Use their common sign as the sign of the sum.

Example Add a. 3 + (5) b. 1 + (15) Solution a. 3 + (5) = 8 = 16

Adding Two Numbers with Different Signs Subtract the smaller absolute value from the larger absolute value. Use the sign of the number whose absolute value is larger as the sign of the sum.

Example Add a. 3 + 12 b. 1 + (9) Solution a. 3 + 12 = 9 b. 1 + (9) = 8

Example Add. a. 4 + (15) = (4 + 15) = 19 b. 4 + (9) = 5 c. 15 + 21 = 6 d. 9.1 + (2.3) = 11.4

Opposites or Additive inverses Two numbers that are the same distance from 0 but lie on opposite sides of 0 are called opposites or additive inverses of each other. The sum of a number and its opposite is 0. If a is a number, – (–a) = a.

Example Find the opposite or additive inverse of each number. a. 9 b. c. 3.5 Solution a. The opposite of 9 is –9. b. The opposite of is c. The opposite of 3.5 is (3.5) = 3.5.

Example Simplify each expression. a. (24) = 24 b. (3y) = 3y c. |9.1| = 9.1