我理解係其實呢度係兩個function嘅difference.
t tends to zero , fx and gx both tends to infinity (dne)
但 fx-gx唔一定跟住dne,個difference 可能隨住兩個function之間嘅convergent rate 接近一個穩定值,咁個穩定值就係個limit,就好似一堆tends to zero嘅sequence form出嚟嘅series sum都唔一定係零咁
呢個只係好intuitive嘅解釋,如果要好正經咁證明就要搬啲epsilon delta出嚟