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4x(2x + 7) << 0

4x = 0 et 2x + 7 = 0

x = 0 et 2x = -7

x = 0 et x = -7/2

x............|-inf..........-7/2........0.........+inf

4x.........|........(-)..............(-)...o....(+)........

2x + 7...|........(-)......o.....(+)........(+)........

Ineq......|........(+).....o.....(-)...o....(+).......

-x(-4x + 1)(x + 6) < 0

-x = 0 et -4x + 1 = 0 et x + 6 = 0

x = 0 et 4x = 1 et x = -6

x = 0 et x = 1/4 et x = -6

x............|-inf.......-6........0.........1/4.........+inf

-x...........|......(+).......(+)...o...(-).........(-)...........

-4x + 1...|......(+).......(+)........(+)...o...(-)..........

x + 6.....|.......(-)...o...(+)........(+).........(+)........

Ineq......|.......(-)...o....(+)..o...(-)..o.....(+)........