2-2 Adding and Subtracting Rational Numbers
Addition of Rational Numbers with the Same Sign
To add rational numbers with the same sign, add their absolute values. The sum has the same sign as the addends.
Addition of Rational Numbers with the Different Sign
To add rational numbers with different signs, subtract the lesser absolute value from the greater absolute value. The sum has the same sign as the number with the greater absolute value.
Additive Inverse Property
The sum of a number and its additive inverse of 0. For every number a, a + (-a) = 0. Example: 2 + (-2) = 0.
Subtraction of Rational Numbers
To subtract a rational number, add its additive inverse. For any numbers a and b, a - b = a + (-b). Example: 8 - 15 = 8 + (-15) or -7