1.5 Adding and Subtracting Real Number

1.5 Adding and Subtracting Real Numbers I. Rules ? The sum of two negative numbers is the negative of the sum of their absolute values. ? Adding numbers with the same sign: To add two numbers with the same sign, add the absolute values of the numbers. The sum has to be the same sign as the given numbers. ? Example: -4+(-3)=-7 ? Adding numbers with different signs: To add two numbers with different signs find the absolute values of the numbers and subtract the smaller absolute value from the larger. Give the answer the sign of the number having the larger absolute value ? Example: -12+6=-6 ? Adding Signed Numbers ? Same Sign - ad the absolute values of the numbers. The sum has the same sign as the given numbers ? Different Signs - Find the absolute values of the numbers and subtract the smaller absolute value from the larger. Give the answer the sign of the number having the larger absolute value. ? Difference - the answer to a subtraction problem ? Definition of Subtraction - for any real numbers x and y: x-y = x+(-y) That is to subtract y from x,add the additive inverse (or opposite) of y to x. ? Three uses of the symbol - ? to represent subtraction, as in 9 - 5 = 4; ? to represent negative numbers, such as - 10, -2, and -3 ? to represent the opposite (or negative) of a number, as in the "opposite (or negative) of 8 is - 8" ? We may see more than one use of - in the same problem such as -6-(-9) where - 9 is subtracted from -6. The meaning of the - symbol depends on its position in the algebraic expression.