<span>6х-2х+(15-3х)
6x-2x+15-3x
x+15
-0.2+15=14.8
</span>
6x^2+15x-54=0
D=225+1926=1521
x1=(-15+39)/12=24/12=2
x2=(-15-39)/12= -54/12= -4,5
6x^2+15x-54=6(x-2) (x+4,5)
6x^2+21x-27=0
D=441+648=1089
x1=(-21+33)/12=12/12=1
x2=(-21-33)/12= -54/12= -4,5
6x^2+15x-54=6 (x-1)(x+4,5)
..................................
A=1 b=9/10 в=1 г=4/5 так думую