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# C3 - Algebraic fractions help please !!

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1. C3 - Algebraic fractions help please !!
Ive attatched a copy of the question I need help with part b

What I did was

x^2+x+1>0

(x+0.5)^2 -1/4+1 > 0

(x+0.5x)^2 +3/4 > 0

Is this enough to show what else should I write ?
Attached Thumbnails

2. Re: C3 - Algebraic fractions help please !!
(Original post by Olive123)
x
You've got the right idea but you've set your answer out wrong. You can't start your answer by writing x^2+x+1>0 because you don't know that yet! Instead, you should say something like:

x^2+x+1 = (x+0.5)^2 +3/4
And since (x+0.5)^2 is greater than or equal to zero, (x+0.5)^2 +3/4 ≥ 3/4 > 0
Therefore, x^2+x+1 > 0
Last edited by electriic_ink; 02-06-2012 at 21:13.
3. Re: C3 - Algebraic fractions help please !!
(Original post by Olive123)
Ive attatched a copy of the question I need help with part b

What I did was

x^2+x+1>0

(x+0.5)^2 -1/4+1 > 0

(x+0.5x)^2 +3/4 > 0

Is this enough to show what else should I write ?
This isn't enough.

You need to say for all values of so for all values of
Last edited by raheem94; 02-06-2012 at 21:15.
4. Re: C3 - Algebraic fractions help please !!
(Original post by electriic_ink)
You've got the right idea but you've set your answer out wrong. You can't start your answer by writing x^2+x+1>0 because you don't know that yet! Instead, you should say something like:

x^2+x+1 = (x+0.5x)^2 +3/4
And since (x+0.5x)^2 is greater than or equal to zero, (x+0.5x)^2 +3/4 >= 3/4 > 0
Therefore, x^2+x+1 > 0
Actually there is a typo in his post.

It should be rather than
5. Re: C3 - Algebraic fractions help please !!
(Original post by raheem94)
Actually there is a typo in his post.

It should be rather than
So there is! Thanks.
6. Re: C3 - Algebraic fractions help please !!
(Original post by electriic_ink)
So there is! Thanks.
No worries

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