I’m guessing that the line is y=-3x and the curve is y=2x²+5x.
They intersect when:
-3x=2x²+5x, 2x²+8x=0, 2x(x+4)=0, so the intersections are (0,0) and (-4,12).
So they do not meet (do not intersect) when x≠0, x≠-4. These (0 and -4) are the only values of x where the line actually intercepts the curve; at all other values of x there is no intersection.
(When x>0 and x<-4 the line is outside the curve.)