Division by zero

Question

Sorry this might sound stupid but I have a question regarding division by zero.

I know division by zero is undefined.

For ex, In DS questions, if its given that x/y > 0. Can we assume that y is not equal to zero?

madhurs254 · Answer

Yes we have to solve it by assuming the same. Or else it will be specifically mentioned in range of y.

blueseas · Answer

IMO if anything is given in denominator such as a/b =>then it means b is not equal to zero.

moreover if the equation is  y = \sqrt{x} 
then it means x will always take positive values.

sguptashared · Answer

hey Madhu,

Yes, we can assume that y is not equal to zero as denominator cannot be zero.

KarishmaB · Answer

You wouldn't even need to assume. Official questions mention explicitly y/x = ... such that  x 
eq 0 .
If somewhere it is not mentioned, you can assume it.

Mind you, that means GIVEN yx = x^2 and NOT GIVEN  x 
eq 0 , you cannot divide both sides by x.
 yx/x = x^2/x  is incorrect.

You must do this:  yx - x^2 = 0 
 x(y - x) = 0 
 x = 0  or  y = x

abhi931 · Answer

yeah its an assumption in gmat that the denominator wont be zero ...in cases where there is some equation in the denominator the denominator will be specifically be pointed to a solution which can lead to a zero ..and in the question stem that possibility is generally refuted..

Division by zero

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