Question

3) x is a positive square root of y and m is the square of y. If x, y, m are nonzero
numbers, what is the relation between x and m?
​

Answer 1

Step-by-step explanation:

Note that .

(1) x = 6. Not sufficient.

(2) y^2 = x^2 -->  --> if  and  have the same sign then  (for example ) but if  and  have the opposite signs then  (for example  and ). Not sufficient.

(1)+(2) We still don't know whether  and  have the same sign or not. Not sufficient.

Answer: E.

About .

The point here is that as square root function cannot give negative result then .

So . But what does  equal to?

Let's consider following examples:

If  --> ;

If  --> .

So we got that:

, if ;

, if .

What function does exactly the same thing? The absolute value function: , if  and , if . That is why 

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