11^x≥1 ∀x real
Deci 3m+18)/(9-m)≥1 \=>
3m+18)/(9-m)-1≥0 .Aduci la acelasi numitor si obtii
(4m+9)/(9-m)≥0
notezi cu Fm fractia si faci tabelul de variatie , alegand intervalele pt care Fm este pozitiva
m l -∞ .................-9/4 ........0..............9 ......+∞
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4m+9l- - - - - - - - - - 0 +++++++++++++++++++
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9-m l++++++++++++++++++++++++++|_ - - - - - - - -
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Fm l_ _ _ _ _ _ _ _ 0++++++++++++++l_ - - - - - -
Deci m∈[-9/4 , 9)
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