Strict inequalities while solving uniform continuity problems in real analysis
Problem - Is g(x) = √ (x2 + 1) uniformly continuous on (0, 1) ?
Solution given -
|g(x)−g(y)| = |√ (x2+1)−√ (y2+1)| = |x2 + y2|/(√ (x2+1)+√(y2+1))
Since x,y∈(0,1), we know ∣x+y∣≤1+1=2
Also, √(x2+1)≥√(02+1)=1, so:
√(x2+1)+√(y2+1)≥1+1=2.
Using the bounds for |x+y| and √(x2+1)+√(y2+1):
∣g(x)−g(y)∣≤∣x−y∣⋅2/2=|x−y|.
so we can use δ=ϵ
My Problem :
Since (0,1) is an open interval then 0,1 ∉ (0,1) and hence |x+y| < 2 and not |x+y| ≤ 2.
And the same goes for √(x2+1)+√(y2+1)≥1+1=2. Instead it should be √(x2+1)+√(y2+1)>1+1=2.
Which further gives ∣g(x)−g(y)∣<∣x−y∣⋅2/2=|x−y|.
Am I correct or incorrect please tell me if I am right or wrong this stuff is really confusing please help me.