What are possible values of x if lne^(2x)/2<xln(3)?lne2x2<xln(3)??

2 Answers
Nov 3, 2015

Question asked for 'values' so you have to state all of them.
x in ]0,oo]x]0,] Notation for the range of zero to infinity but excluding 0

Explanation:

ln(e^(2x)) ln(e2x) has the same value as 2xln(e)2xln(e)
ln(e) = 1ln(e)=1 so we now have:

(2x)/2 < x ln(3)2x2<xln(3)

x < x ln(3)x<xln(3)

0 < xln(3) - x0<xln(3)x

0< x(ln(3) -1)0<x(ln(3)1)

0/(ln(3) -1) < x0ln(3)1<x

x > 0x>0

Nov 3, 2015

This inequality is true for any positive real number x in (0;+oo)x(0;+)

Explanation:

ln(e^(2x))/2 < xln(3)ln(e2x)2<xln(3)

(2xlne)/2 < xln32xlne2<xln3

x < xln3x<xln3

x(1-ln3) < 0x(1ln3)<0

x>0x>0

I changed the sign of inequality in last expression because ln3~~1.098ln31.098, so last step was the division by a negative number (1-ln31ln3)