Notezi fractia cu F, si aplici regula semnelor pt inmultire:(+)*(-)=( -) si (+)*(+)*(+)=(+)
Pt x=2 si x=4 numitorul se anuleaza, deci fractia nu exista in x=2 si x=4
Mai intai anulezi fiecare paranteza in parte
x-1= 0
(x-2)=0
x-3=0 x=3
x-4=0 x=4
Tabelul de variatie al fractiei F
__xl-∞_________________0___1___2___3___4____________+∞
x-1 l - - - - - - - - - 0 + + + + + + + + +
x-2 l - - - - - - - - - -0+ + + + +
x-3 l- - - - - - - - - - - 0+ + + + + +
_________________________________________________________-
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x-4 l- - - -- - - - - - - - 0 + + + +
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F l + + + + + + + 0 _ _ l + 0 - - l + + + +
Se aleg numai intervalele pozitive
X∈(-∞ ,1]U(2 ,3]U(4 ,∞)
