1. x²-5x+4=0
delta=(-5)²-4×4×1
delta=25-16
delta=9
x1=(5-3)/2. x2=(5+3)/2
x1=1. x2=4
2. x²-5x+6=0
delta=(-5)²-4×6×1
delta=1
x1=(5-1)/2. x2=(5+1)/2
x1=2. x2=3
3. x²-5x=0
x(x-5)=0
x1=0. x2-5=0
x2=5
4.x²-5x-6=0
delta=(-5)²+4×6×1
delta=25+24
delta=49
x1=(5-7)/2. x2=(5+7)/2
x1=-1. x2=6
5. x²-5x-14=0
delta=(-5)²+4×14×1
delta=25+56
delta=81
x1=(5-9)/2. x2=(5+9)/2
x1=-2. x2=7