Find the range of values of c for which the line y=c(x-3) does not intersect the curve y+2x=x^2+6

i equate the two eqn together. x² + 6 -2x= cx -3c

and i put b²-4ac<0

so i get (-2-c)² - (24-12c)<0

then i am stuck i dont know how to find the range of values for c