(х+3)(4х-1-4х-12)=13
(х+3)(-13)=13
х+3=-1; х=-4.
4x^2-x+12x-3-4(x^2+6x+9)-13=0
4x^2-x+12x-3-4x^2-24x-36-13=0
-13x-52=0
-13x=52
x=52/(-13)
x=-4
(х+3)(4х-1-4х-12)=13
(х+3)(-13)=13
х+3=-1; х=-4.
4x^2-x+12x-3-4(x^2+6x+9)-13=0
4x^2-x+12x-3-4x^2-24x-36-13=0
-13x-52=0
-13x=52
x=52/(-13)
x=-4