Lab 2 question 183

[sywillis16]

Is the answer for this question in Lab 2 incorrect. The instructer solves the first question of DS listing only positive numbers, but negative numbers can also work for this answer

he lists 2, 3, 4, 5 which are all greater than 1 when squared but what about -2 , -4, -4 they are also numbers that can alse be squared and give values greater that 1. If these are included the question IS and not a Yes.

Am I thinking of this incorrectly. I would go look this up in OG but i am away on business and wont be back for a little while.


Thanks

Selene

[dbernst]

Selene,

We would be glad to address your question, but could you please post the entire text of the problem? Many readers of the forums do not have access to these problems, and we definitley want to make the forums valuable not only for the poster but also for all future readers.

Many thanks!
-dan

[Selene]

is X squared greater than X?

1) X squared is greater than 1
2) X is greater than -1



thanks Dan I will post the Q from now on.



[quote="sywillis16@YAHOO.COM"]Is the answer for this question in Lab 2 incorrect. The instructer solves the first question of DS listing only positive numbers, but negative numbers can also work for this answer

he lists 2, 3, 4, 5 which are all greater than 1 when squared but what about -2 , -4, -4 they are also numbers that can alse be squared and give values greater that 1. If these are included the question IS and not a Yes.

Am I thinking of this incorrectly. I would go look this up in OG but i am away on business and wont be back for a little while.


Thanks

Selene[/quote]

[shaji]

The correct answer is C; since taking both ststements enables you to be ceratin that X>1 and finally a definite Yes to the question.

is X squared greater than X?

1) X squared is greater than 1
2) X is greater than -1



thanks Dan I will post the Q from now on.

Is the answer for this question in Lab 2 incorrect. The instructer solves the first question of DS listing only positive numbers, but negative numbers can also work for this answer

he lists 2, 3, 4, 5 which are all greater than 1 when squared but what about -2 , -4, -4 they are also numbers that can alse be squared and give values greater that 1. If these are included the question IS and not a Yes.

Am I thinking of this incorrectly. I would go look this up in OG but i am away on business and wont be back for a little while.


Thanks

Selene

[StaceyKoprince]

You indirectly alluded to the fact that this is an OG question - please make sure to make that explicit, as we have to give proper copyright credit to the authors. This is OG Q DS 78.

is X squared greater than X?

1) X squared is greater than 1
2) X is greater than -1

(1) x^2 > 1.
- If we try x = 2, this satisfies statement 1, so x=2 is a valid number to try. Then, we plug x=2 into the question and, yes, x^2 is greater than x.
- Next, try x = -2. This satisfies statement 1, so x=-2 is a valid number to try. Then, we plug x=-2 into the question and, yes, x^2 is still greater than x.

You are correct that we can try negative numbers here, but they do not change the outcome of the problem - when we square x in the question, it always becomes positive.

- Next, try x=0. Can't try this because it doesn't satisfy statement 1. How about x = 1/2? Nope, doesn't satisfy statement 1. If you keep going with this, you'll see you can only numbers greater than 1 or less than -1 satisfy statement 1, so those are the only valid numbers to try here. If we're limited to those numbers, then x^2 will always be greater than x, in which case, statement 1 is sufficient.

(2) X is greater than -1
- If we try x = 2, this satisfies statement 2, so x=2 is a valid number to try. Then, we plug x=2 into the question and, yes, x^2 is greater than x.
- If we try x = 0, this satisfies statement 2, so x=0 is a valid number to try. Then, we plug x=0 into the question and, no, x^2 is not greater than x.
Two contradictory answers (yes and no) means this statement is insufficient.

Answer is A.