For first one i think it should be 4 only bro
as we get the quadratic as 4x^2+2ax+1>0
for this D<0
a can be only -1,1 then
It's less than sign not ≤
Here bro for 2 and -2
expression is (2x-1)^2 and ,(2x+1)^2
But strictly speaking should not it be 2 only? (Answer)
I think for 2 and -2 also the graph is concave upwadrs.
How? Please explain.
Put that values in origional expression bro and check graph once.
I am also getting 2 for first one.
a = 4 gives a small convex section
Thanks for confirming!
sorry bro @above but you have to check for a= -2,+2
And here you can see they are strictly following what is needed.
For concave upward along entire number line, f''(x)>0
But for a=-2,2 it touches x-axis
For any a in (-2,2) it is above x-axis