Help needed with p1 math MJ 2005

[Mohammad Aamer]

How am I supposed to do 10(i)? How am i supposed to show that the curve lies above the x axis? I've heard that we can show that b^2-4ac<0 in such cases....is that method acceptable? The mark scheme doesnt say anything abt it...help pls and quickly..no need to go into detail..just give me the outline .

 

[XWTBSILT]

It should be accepted coz if b^2 -4ac < 0 then no real roots.
Although they havent mentioned it

 

[ahad]

yes that method is valid. Best of luck