14-(2+3x-x^2)=x^2+4x-9
14-2-3x+x^2-x^2 - 4x+9=0
21-7x=0
-7x=-21
X=3
14-2-3х+х^2=х^2+4х-9 12-3х+х^2-х^2-4х+9=0 21-7х=0 -7х+21=0 -7х=-21 х=(-21)/(-7) х=3