Please Solve? Algebra Help?

Question

Please solve these:

1. Write a rule for adding two negative numbers without using a number line. Then use this rule to find the sum -43+ (-118)

2. Is [a+b] = [a] + [b] true for all numbers a and b? if not, give a counterexample.

Answer 1

for number one i think the answer would be a negitive plus a nagitive equals a negitive. and -161

number 2: i think so...

Answer 2

1. The sum of two negative numbers is the negative sum of their positive counter parts. Or a negative plus a negative equals a negative. (-a+ -b= -|a+b|).

-43+ (-118) = -161

2. If those are brackets then it's true. If those are absolute values signs, no it is not true for all numbers. A counterexample would be -1 and 1.

Let a=-1 and b=1

|a+b| = |-1+1| = 0

|a|+|b| =|-1| + |1| =2