uwengdori wrote:

I think I am confused as to when I can cancel out variables.

For example,

3w^2 = 6w

3w = 6

w=2

I'm aware that cancelling w's on both sides make me lose of the x solutions, so I should not cancel out w.

Now if we look here ,

x^2 - y^2 = x - y

(x+y)(x-y) = (x-y)

{(x+y)(x-y)}/(x-y) = (x-y)/(x-y)

(x+y) = 1

This is valid.

However, when I'm thinking inside my head, I feel hesitant to perform cancellations like that because I am scared I might lose possible actual answers like the one I mentioned above. This makes me scared, panic and make me lose time.

Any definite approach and proper concept that could help me think straight and confident regarding this situation?

Thanks,

Hi uwengdori,

I will try and answer your question.

The variables are generally cancelled when they are of same sign.

Case 1 :3w^2 = 6w

In Gmat, It is not wise to cancel out and for the above you can do it as below

3w^2- 6w = 0

3W (W-3)=0--------> 3W=0 or W=0 or W=3....So there are 2 solutions to this question

In the second question x^2-y^2= x-y....Let us follow the same method

Taking (x-y) common we get ----> (x-y){x+y-1} =0 or x=y or x+y=1

For more on these, please refer to Math club chapters on Algebra...

The link is

algebra-101576.html#p787276Happy Gmating!!!!

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