e) x²-9>0
(x-3)(x+3)>0
x=3 x=-3
x∈(-∞;3)∪(3;∞)
b) x²-5x≥0
x(x-5)≥0
x=0 x=5
x∈<0;5>
c) -x²+x+2≥0
Δ=1+8= 9
√Δ= 3
x1= -1+3/-2= 2/-2= -1
x2= -1-3/-2= -4/-2= 2
x∈<-1;2>
