Question: Conclusion Based on Root

Comment on Conclusion Based on Root

3.5 is not integer it is real
greenlight-admin's picture

That's correct. So, we can automatically rule out 3.5 as a possible solution.

One of the rule says if x > 1, then √x is less than x.
I thought of the same rule while encountering the question. But then I have a doubt why we took 0 as well?
greenlight-admin's picture

You're correct to say that, if x > 1, then √x < x, however this rule applies to x-values that are greater than 1.

When it comes to √0, the same rule does not apply.
Here, √0 = 0

Does that help?

Cheers,
Brent

As I go on solving the question, i often ignore the given premises of question. Here, I thought 3.5 is also the answer, as its root is lesser than 2. I never cared that x must be a integer.
I must be more careful about not ignoring the premise while solving.
greenlight-admin's picture

I agree!
I often miss seeing important words (like INTEGER, POSITIVE, or CONSECUTIVE), which totally throws off the solution.

Hi Brent,

1.4 and 1.7 are also not integers? Why are we selecting these then?

Thanks,
Ketan
greenlight-admin's picture

We're not selecting 1.4 and 1.7 as possible values of x.
We're selecting 2 and 3 as possible values of x.

We're told that √x < 2
If x = 2, then √2 ≈ 1.4
Since 1.4 < 2, we know that x = 2 is a solution to the inequality √x < 2

Likewise, since √3 ≈ 1.7, and since 1.7 < 2, we know that x = 3 is another solution to the inequality √x < 2

Does that help?

Cheers,
Brent

Tricky! 3.5 is not an integer, so you have to be careful about that. If you miss that, you get the WHOLE question wrong. That's the part about questions like these that can make you blow your lid....the fact that no partial credit is given. Really terrible.
greenlight-admin's picture

That's right. Some of the most common/crucial words that students often miss include:
- POSITIVE
- NEGATIVE
- INTEGER
- NON-NEGATIVE
- DIFFERENT (as in "x, y, and z are DIFFERENT positive integers")

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