The limit (as 'x' approaches zero) of x²/(2x+1) is
0 / (0+1) = 0 .
You get this by substituting the limit in place of 'x'.
Sometimes that doesn't work. Sometimes it gives you
monstrosities like 0/0, or 1/0, or ∞/∞ .
But it works for this one. There's nothing wrong with 0/1 = zero .