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# C1 question watch

1. Now if i multiply both sides by and then subtract from both sides , I get :

But if I directly subtract from both sides, I end up with :

Shouldn't i get the same fraction from both methods?
Where am I going wrong?
2. No, you shouldn't get the same fraction. It's an inequality, not an equation/identity.
3. Woops.
4. (Original post by princejan7)
Shouldn't i get the same fraction from both methods?
Where am I going wrong?
You're going wrong in assuming you should have the same result by both methods.

Lets take a more obvious example.

4 > 2

Divide by 2,

2 > 1

and subtract 1 to get:

1 > 0

Or the other way, from

4 > 2

subtract 2 to get

2 > 0.

Both are correct, as in your example.

If you want to get to your first result, from the second, you need to divide by 2 here, or by k in your example.

Edit: I am assuming k > 0, otherwise the first method would be incorrect.
5. Anyway, just to make clear, your first attempt is not correct because the value of k is indetermined. Second attempt is better.
6. (Original post by Dekota-XS)
Anyway, just to make clear, your first attempt is not correct because the value of k is indetermined. Second attempt is better.
what if it was given that k >0?
7. (Original post by princejan7)
what if it was given that k >0?
If k > 0 the first attempt is fine, AND does lead to different results; see my previous post.

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