x^2-8x+15=0
x1=5
x2=3
15-x^2=0
x=sqrt(15)
x=-sqrt(15)
1) x>=5 x^2-8x+15<=-15+x^2 -8x<=-30 x>=15/4 x>=5
2) ]sqrt(15);5[ -x^2+8x-15<=x^2-15 2x^2-8x>=0 2x(x-4)>=0 [4;5]
3) ]3;sqrt(15)] -x^2+8x-15<=15-x^2 8x<=30 x<=15/4 <strong>]3;15/4]
4) ]-sqrt(15);3] x^2-8x+15<=15-x^2 2x(x-4)<=0 [0;4] <strong>[0;3]
5) x<-sqrt(15) x^2-8x+15<=x^2-15 8x>=30 x>=15/4
[0;15/4] U [4;бесконечность[