Objective: To add and subtract real numbers using rules.
If both number (a and b) are positive then just add the numbers and keep the positive sign. a + b = ∣a∣+∣b∣ Ex: 6 + 8 = 14 If both number (a and b) are negative then just add the numbers and keep the negative sign. a - b = -( ∣a∣+∣b∣) Ex: -6 + (-8) = -14
If a is positive and b is negative take the difference of the two and then the sign of the number with the greater absolute value. a + b = ∣a∣-∣b∣ a has a greater value or a + b = - ( ∣b∣-∣a∣) b has the greater value Ex: 9 + (-4) = 9-4 = 5 3 + (-7) = -(7-3) = -4 If a and b are opposites, then a + b = 0
Definition of Subtraction – For all real numbers a and b, the difference a-b is defined by a-b = a +(-b) (To subtract- turn the problem into an addition problem with the opposite of the second number b.) Example: -6 – (-10) = - 6 + 10 = 4