1. This is called the limit, which is read as "X approaches A" in brackets. The whole reading is when X approaches A, the limit of Y = when X approaches A, the limit of F (X) = K. This is the content of high numbers, and you will know it when you go to college.

2. The symbol ""represents a power, for example, 2 represents a power of 2, that is,

(-1) power of (n+ 1)