Odpowiedzi

2010-03-11T12:46:41+01:00
A)x^3+x^2-25x-25>0
x^3+x^2-25x-25=0
x²(x+1)-25(x+1)=0
(x²-25)(x+1)=0
(x-5)(x+5)(x+1)=0
x=5 x=-5 x=-1

x∈(-5;-1)u(5;∞)
b)x^3-4x^2<0
x^3-4x^2=0
x²(x-4)=0
x=0 x=4
x∈(0;4)

c) (x+1)(x^2+2x-3)>>0
(x+1)(x^2+2x-3)=0
x=-1 Δ=2²-4*1*(-3)=16
x1=-2-√16/2=-3
x2=-2+√16/2=5
x∈<-3;-1>u<5;+∞)
d) (x^2-6x+5)(x^2+4x)<<0
(x^2-6x+5)(x^2+4x)=0
(x^2-6x+5)x(x+4)=0
Δ=-6²-4*1*5=16 x=0 x=-4
x1=6-√16/2=-1
x2=6+√16/2=7
x∈(-∞;-4>u<0;7>