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hendricks_intermediate_algebra_1e_ch1_3

16 Chapter 1 Real Numbers and Algebraic Expressions temperature at 1 p.m. is 15°F. We represent this numerically and graphically as shown. +20 –20 –15 –10 –5 0 5 10 15 20 25 30 -5 + 20 = 15 So, there are four different cases of adding real numbers based on the signs of the numbers. Procedure: Adding Real Numbers Step 1: Determine the signs of the numbers being added. Step 2: Add the numbers according to the following rules. a. If the signs are the same, add the absolute values of the numbers and Subtracting Real Numbers To determine how to subtract real numbers, we rely on two facts that we already know. 6 - 4 = 2 and 6 + (-4) = 2 Since these two statements produce the same result, it must be true that 6 - 4 = 6 + (-4) These expressions indicate that subtraction is a form of addition. Subtraction is equivalent to adding the opposite of a number. Property: Subtracting Real Numbers For real numbers a and b, a − b = a + (−b) keep the sign. b. If the signs are different, subtract the absolute values. The sign of the result is the sign of the number with the larger absolute value. Procedure: Subtracting Real Numbers Step 1: Change the subtraction sign to addition and write the opposite of the number being subtracted. Step 2: Apply the rules for adding real numbers to obtain the result. Note: If three or more numbers are added or subtracted, add or subtract from left to right.


hendricks_intermediate_algebra_1e_ch1_3
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