18x²-3x-21=18(x+1)(x-7/6)
D=9+1512=1521
√D=39
x1=(3-39)/36=-1
x2=(3+39)/36=7/6
18x²-33x+14)=3)x-2/3)(x-7/6)
D=1089-1008=81
x1=(33-9)/36=2/3
x2=(33+9)/36=7/6
(18x²-3x-21)/(18x²-33x+14)=18(x+1)(x-7/6)/18(x-2/3)(x-7/6)=
=18(x+1)/(x-2/3)=18(x+1)/6(3x-2)=3(x+1)/(3x-2)