Basic Properties of Numbers: Solving Inequalities

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Homework Statement


Find all number x for which 5-x^2 < 8


Homework Equations





The Attempt at a Solution


Adding -5 from both sides we get -x^2 < 3
x^2 > -3
then it is impossible that x > sqrt -3...
Any idea how to solve this step bystep
 
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If you think about, you're asking when is five minus a positive number less than eight, and the answer to that is always, (-\infty, \infty).
 
Analysisfreak said:

Homework Statement


Find all number x for which 5-x^2 < 8


Homework Equations





The Attempt at a Solution


Adding -5 from both sides we get -x^2 < 3
x^2 > -3
then it is impossible that x > sqrt -3...
Any idea how to solve this step bystep

Not only is it possible for x2 to be greater than -3, since x2 is always non-negative it is always true!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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