Functions are bounded, unbounded, convergent, divergent, with and without limits. What are the relations between these relations?

Functions are bounded, unbounded, convergent, divergent, with and without limits. What are the relations between these relations?


If a function is monotonically bounded, it must have a limit, and if there is a limit, it must converge
There is no limit to the divergence of unbounded functions
If it's convenient, I'll check the gaoshu book. It's very detailed



Given that f (x) is a quadratic function, the vertex of its image is (1,3), and it passes through the origin, find f (x)


By vertex
f(x)=a(x-1)²+3
Over origin
x=0,y=0
0=a(0-1)²+3
a=-3
f(x)=-3x²+6x



Let f (x) = {x ^ 2 + 2x + 1, X ≤ 1, x, 1


f(1)=4≠1
Therefore, the limit does not exist when x → 1
f(2)=2=2
lim(x→2)f(x)=2
im(x→3.5)f(x)=5