As the title suggests,i can't figure out when to be wary of the "could be positive or negative,so we can't say" rule in algebra.Please help in understanding this.
Acc. to the books,if x^2 is lets say 25,x could be positive or negative both so we cant say what the result could be when we use x in any other calculation.That is fine.Great.
Next is √x^2= |x|
Coz we take square of x and x becomes +ve and then ROOT INSTRUCTS US TO TAKE ONLY THE POSITIVE VALUE OF X.
Is x > y?
(1) x^2> y^2
So,here if we take the root on both sides of the equation,will we not get x>y???Please correct me if i am wrong or missing something here.
(2) x - y > 0
Answer is B.
Bunuel , insights please!!