X²-8x+15≥0
x1+x2=8 U x1*x2=15
x1=3 U x2=5
+ _ +
---------------[3]----------------------[5]------------------
x∈(-∞;3] U [5;∞)
--------------------------------------------------------------------------
2/x-3/(x-4)<5/2<br>[2(x-4)-3*x-5x(x-4)]/[x(x-4)]<0<br>(2x-8-3x-5x²+20x)/[x(x-4)]<0<br>(5x²-19x+8)/[x(x-4)]>0
5x²-19x+8=0
D=361-160=201
x1=(19-√201)/10 U x2=(19+√201)/10
x(x-4)=0
x=0 x=4
+ _ + _ +
----------(0)----------((19-√201)/10)----------((19+√201)/10-----------(5)----------
x∈(-∞;0) U ((19-√201)/10;(19+√201)/10) U (5;∞)