Bonsoir,
(x + 3)^2 > 9x^2
(x + 3)^2 - 9x^2 > 0
(x + 3 - 3)(x + 3 + 3) > 0
x(x + 6) > 0
x = 0
x + 6 = 0 => x = -6
x......|...-inf .........-6.........0.........+ inf
x......|...........(-)..................||....(+).......
x+6.|...........(-)......||.......(+)................
Eq...|...........(+).....||...(-)....||.....(+).......
x € ] -inf ; -6[ U ]0 ; + inf[
1/(x + 2) << 4/(4 - x^2)
1/(x + 2) - 4/(2 - x)(2 + x) << 0
(2 - x - 4)/(2 - x)(x + 2) << 0
(-x - 2)/(2 - x)(x + 2) << 0
-(x + 2)/(2 - x)(x + 2) << 0
-1/(2 - x) << 0
Avec 2 - x # 0
x # 2
x..........|.....-inf..............2..............+inf
2-x.......|..............(+).......||.......(-)..........
-1.........|..............(-)..................(-).........
Eq......|............(-)............||........(+)........
x € ]-inf ; 2 [
Je te laisse faire la dernière