Logarithmic inequility (lg)

Algebra 2

Logarithmic inequility (lg)

Postby lukash » Fri Oct 26, 2007 5:02 am

lg4x - 5lg2x + 6 < 0 ???
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Postby Math Tutor » Fri Oct 26, 2007 5:10 am

lg2x = t

so we have the followin inequility:

t2 - 5t + 6 < 0

Can you solve it, please and I will finish the problem.

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lukash

Postby lukash » Fri Oct 26, 2007 6:53 am

[tex]u_1 = 3[/tex] and [tex]u_2 = 2[/tex].
And then lg2x = 3
lg2x = 2
And here i can't continue ???

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Postby Math Tutor » Fri Oct 26, 2007 8:53 am

lg2x = t
lg x = √t
lgx = √t.lg10
lgx = lg102√t
x = 10√t


u1 and u2 are the solutions of the equation.
The solution of the inequility t2 -5t + 6 < 0
The solution is t in (2, 3)

so x in (10√2, 10√3)

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Postby Math Tutor » Fri Oct 26, 2007 9:00 am

If you have not understand something you can ask me questions.

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lukash

Postby lukash » Fri Oct 26, 2007 9:57 am

thank you very much :)
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