1) x^2 - 2x -18 =6
or x^2 -2x -24 =0
or x^2 -6x +4x -24 = 0 , using the splitting the middle term method
or x(x-6) + 4(x-6) =0
or (x+4) (x-6)=0
So, x= -4 or x =6
2) 2x^2 +5x +18 = -6x +3
or 2x^2 +5x + 18 +6x -3 =0
or 2x^2 +11x +15 =0
or 2x^2 + 6x + 5x +15 =0
or 2x( x+3) + 5(x+3)=0
or (2x +5) (x+3) = 0
x = -5/3 or x= -3
3) 3 -14x = 5x^2
or 5x^2 +14x -3=0
or 5x^2 +15x -x -3 =0
or 5x( x +5) -1(x+3) = 0
or (5x-1)(x+3) =0
so, x =1/5 or x = -3