极限的和就是和的极限，这个理论如何应用到生活中?股票投资中

How do you handle this? Well, the first thing to note is that you can bust up this last expression into four separate limits. So if you know what happens to the four quantities 1, −1000/3x, 5/3x2, and −7/3x3 as x becomes verylarge, then you can just add the four limits together to get the limit you want. Technically, this could be described in words as “the limit of the sum is equal to the sum of the limits”; this is true when all the limits are finite.∗