$\lim_{h \to 0} \frac{1 \cdot (2+h)^2 - 1 \cdot 2^2}{h} = 4$

$\lim_{h \to 0} \frac{(1+h) \cdot 2^2 - 1 \cdot 2^2}{h} = 4$

$\lim_{h \to 0} \frac{1 \cdot (2+h)^2 - 1 \cdot 2^2}{h} = 2$

$\lim_{h \to 0} \frac{(1+h) \cdot (2+h)^2 - 1 \cdot 2^2}{h}$ does not exist