Zamala wrote:

I agree with Runnyboy44's doubts about the answer. How are we supposed to know that we do not have to consider the case - -(|-3|) = +3 in this case?

This doubt could be corroborated by looking at exercises where the function is defined as a # b = (+)|a + b|. Then I would seperate between case 1:

a # b = (+)|a + b|

and case 2: a # b = (-)|a + b|

.

how are we supposed to that we should limit our answer strategy to plugging in.

Hi..

we have to just read the information given in the question while we solve a question.

The question gives us a function a # b = (-)|a + b|...

Now you have to find (-10)#7, this means a=-10 and b=7, so substitute in the function to get (-10)#7=-|-10+7|=-3

|a|=-a when a<0.. But this is true when you do not know the value of a. Here you know what a and b stands for..

Even here a+b=-10+7=-3<0 so |a+b|=-(a+b) when (a+b)<0 thus |-10+7|=-(-10+7)=-(-3)=3..

But we are looking for -(|a+b|), which will be equal to -(3)

_________________

Some useful Theory.

1. Arithmetic and Geometric progressions : https://greprepclub.com/forum/progressions-arithmetic-geometric-and-harmonic-11574.html#p27048

2. Effect of Arithmetic Operations on fraction : https://greprepclub.com/forum/effects-of-arithmetic-operations-on-fractions-11573.html?sid=d570445335a783891cd4d48a17db9825

3. Remainders : https://greprepclub.com/forum/remainders-what-you-should-know-11524.html

4. Number properties : https://greprepclub.com/forum/number-property-all-you-require-11518.html

5. Absolute Modulus and Inequalities : https://greprepclub.com/forum/absolute-modulus-a-better-understanding-11281.html