Section 1.4 Addition of Real Numbers 47 �� ������������������������ ������������������ A problem and an incorrect solution are given. Provide the correct solution and an explanation of the error. 4a. 7 + (-11) �������������������������������������� ���������������������������������������������������������������� Since the signs are different, we should subtract the absolute values of the numbers and take the sign of the number with the larger absolute value. The difference of the absolute values is 4 but -11 has the larger absolute value, so the sign of the answer should be negative. 11 7 + (-11) = -4 4b. -5 + (-4) �������������������������������������� ���������������������������������������������������������������� Since the signs are the same, we should add the absolute values of the numbers and keep the sign the same. So, the correct solution is -5 + (-4) = -9 7 + (-11) = 4 -5 + (-4) = -1 SUMMARY OF KEY CONCEPTS 1. To add numbers with the same sign, add their absolute values and keep the sign. 2. To add numbers with different signs, subtract the absolute values of the numbers. The sign of the answer is the sign of the number with the larger absolute value. 3. When solving real-life applications, look for the key phrases to determine how to solve the problem. GRAPHING CALCULATOR SKILLS ( ( ) 4 ) + ( ( ) ) ENTER Very important: Please note the difference between a negative sign and the subtraction sign. Use the negative sign (-) to denote the sign of a number and the subtraction sign to perform an operation with numbers. ANSWERS TO STUDENT CHECKS Student Check 1 a. 8 b. -7 c. -3.9 d. 5 6 e. - 11 15 f. - 11 2 g. -12 Student Check 2 a. -8 b. 4 c. -12 d. 12.2 e. 0 f. - 7 8 g. 4 Student Check 3 4.83°F In this section, the calculator will help you confirm your work. You should be able to enter operations with signed numbers. Example: Simplify (-4) + (-7).
hendricks_beginning_algebra_1e_ch1_3
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