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by DanaJ » Sat Mar 14, 2009 9:49 am
1 - x^2 >= 0 - multiply by (-1) to get a clearer picture:
x^2 - 1 <=0
x^2 <= 1.
This means that x is going to be between -1 and 1, with answer E

I suppose you got confused because of the way it was written: it was indeed kindda tangled...
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by dendude » Mon Mar 16, 2009 7:52 am
DanaJ wrote:1 - x^2 >= 0 - multiply by (-1) to get a clearer picture:
x^2 - 1 <=0
x^2 <= 1.
This means that x is going to be between -1 and 1, with answer E

I suppose you got confused because of the way it was written: it was indeed kindda tangled...
OR, use the a^2 - b^2 = (a+b)(a-b) formula
1-x^2 >=0
(1-x)(1+x)>=0

(1-x) >=0
-x>=-1
x<=1

(1+x)>=0
x>=-1

So therefore, -1<=x<=1
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