x2
x
=0
-18x2+21x
-18x2+21x-6=0
-18x2+21x-5=0
-18x2+21x-3=0
-18x2+21x+4=0
-18x2+21x+9=0
-18x2+21x+15=0
-18x2+21x+22=0
-6
-5
-3
4
9
15
22