Réponses

2013-05-16T19:31:13+02:00

attention à ne pas multiplier par 3(x+27)

x+15>2/3(x+27) => x+15 - 2/3(x+27) > 0 => (3(x+27)(x+15) - 2)/3(x+27)> 0

=> (3x² + 126x + 1213)/3(x+27)> 0

                          x            -27,05              -27                    -14,94

3x² + 126x + 1213      +       0           -                    -               0            +

                     x+27      -                     -        0           +                            +

 

f(x)                               -        0         +         |            -              0            +

solution -27,05 < x < -27    U  x > -14,94

2013-05-16T19:31:26+02:00

x+15>2/3(x+27)

x+15> 2/3 x + 2/3*27

x+15>2/3x + 18

x-2/3 > 18-15

-1/3 x > 3

-1/3 x<3

x<(-3/1)*3 = -6