What are the perfect standard steps required by the landlord? . What I want to say is that you don't need to write so perfectly when you answer questions. What is perfection? As long as you can understand it, so can the teacher. Mathematics is rigorous, but there is no standard. I think the following writing is enough. . If not, you can copy it verbatim in the book.

I just learned advanced mathematics, too. I hope these are helpful to you.

When 1.x approaches 3,

Because this is a piecewise function, we can find the limit when x approaches 3+ and 3- respectively.

X approaches 3+ lim f(x)=lim x+ 1=4.

X approaches 3- lim f(x)=lim 7-x=4.

Because the above results are equal, the limit is 4 when x approaches 3.

2. when x approaches 0, f (x) = 7-x.

So lim f(x)=7.