OG DS #57

[erdnah]

Hi,

I've got a question; perhaps some can help me with that?!



With my last operation I got x+y=0, thus at least A or D would have to be correct...

erdnah

[chatekar]

erdnah,

To find the value of 1/X + 1/Y i.e. (X+Y)/XY, so you need two things,
first is X+Y and the second is XY.

Both are given in statement 1 and 2 so you need both the statements together.

Hope this helps

Thanks

[erdnah]

@chatekar, yeah, i found that information also in the og

but what i really want to know is, why i can't multiply the last term with xy, so that i would get x+y = 0!? i feel terrible stupid

[chatekar]

If you are multiplying by xy to get the value of the given expression, then you are changing the value of the given expression.
You can't simply multiply by xy, you also need to divide by xy so that value of the expression doesn't change.

Am I making sense?

Thanks

[erdnah]

Yeah, of course you do... :roll:
There are days, I should have stayed in bed.

[erdnah]

It seems as if I did the same mistake today again :roll:

When there is x = x², I divided both sides by x. I though I would get 1 = x which seemed to be wonderful in my eyes... but x could also be 0!

What was this time (or as on the problem above) my mistake in thinking?

Hope someone can help me..

[bingojohn]

It seems as if I did the same mistake today again :roll:

When there is x = x², I divided both sides by x. I though I would get 1 = x which seemed to be wonderful in my eyes... but x could also be 0!

What was this time (or as on the problem above) my mistake in thinking?

Hope someone can help me..

Solve equation:

x^2 = x
x^2 - x = 0
x(x - 1) = 0

x = 0 OR x = 1

hope this helps...