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Algebra

inequalities with natural log and exponents

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markmil2002
Average Member

USA
11 Posts

Posted - 09/06/2007 : 12:05:15

I cant figure out where to start on this problem.

((2e^-x)-(xe^-x))/(1-x^2) > 0

pka
Advanced Member

USA
2731 Posts

Posted - 09/06/2007 : 13:49:10

Because e^-x is always positive, it contributes nothing to the problem.

Therefore, just solve (2-x)/[(1-x)(1+x)]>0.
Here the critical numbers are 2, 1, & -1.
Use those to find the intervals where the statement is true.

markmil2002
Average Member

USA
11 Posts

Posted - 09/06/2007 : 14:25:13

Thanks. I assumed that e could be removed from the equation, but my problem was that I forgot about setting a problem up with the intervals. I took a little brake from math and I'm a little Rusty now, lol.

sahsjing
Advanced Member

USA
2399 Posts

Posted - 09/06/2007 : 18:20:41