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a)
(x²+2x+1)(x²-4)>0
(x+1)² * (x+2)(x-2)>0
x+1=0 dla x=-1 ma wszystkie wartosci nieujemne.
____-2____-1____2_____>
+ + 0 _ _ 0 _ _ 0 + +
Odp. x∈(-∞,-2) u (2,+∞)
c)
x^4 < 8x
x (x³-8) <0
m.z. x=0 v x=2
_____0_____2_____>
+ + 0 _ _ 0 + +
Odp. x∈(0,2)
l)
2x³-3x²-10x+15 ≤0
x²(2x-3)-5(2x-3) ≤ 0
(2x-3)(x²-5) ≤ 0
(2x-3) (x+√5)(x-√5) ≤ 0
m.z. x=3/2 v x=-√5 v x=√5
_____-√5_____3/2____√5______>x
_ _ 0 + + 0 _ _ 0 + +
Odp. x∈(-∞,-√5> u <3/2, √5>
2.
a)
x³-4x²≥0
x²(x-4)≥0
D={{0} u <4,+∞)}
b)
x³-4x>0
x(x²-4)>0
x(x+2)(x-2)>0
___-2___0___2____>x
_ _ 0 + + 0 _ 0 + +
D={(-2,0) u (2,+∞)
c)
x³+x²≥ 0 i x³-16x≥0
x²(x+1)≥0 i x(x+4)(x-4)≥0
___-1____0_____>x i _____-4_____0_____4______>x
_ _ 0 + + 0 + + _ _ 0 + + 0 _ _ 0 + +
x∈<-1,+∞) i x∈<-4,0> u <4,+∞)
D=<-1,0> u <4,+∞)