@Carl Love Sorry, I didn’t make it clear. I mean to remove terms containing** a **and** exactly one other variable**. But I have to say that the answers you provide later are very beautiful and practical, and

**sometimes they will be used**.

**I hope you don’t delete it though they are a little bit different from what I meant here.**

We may think about it a little bit more. Now we just delete "ab", "ac" and “ad” and so on. I mean all the "a*x" forms that have "a" in them need to be deleted. Note that "x" stands for *exactly one* letter. For exampleï¼š

**f :=a*b*c*d+ a*b*c+a*b+a*c+a*d+a*e+2*a+a+b+c;**

s:=select(has, {op(f)}, a) minus {a*b,a*d,a*c,a*e};

s:=select(has, {op(f)}, a) minus {a*b,a*d,a*c,a*e};

s := {a*b*c, a*b*c*d, 3*a}

The above expression *f* is simple, so the above method can be done. But if there are many kinds of a* x in *f*, the codes may not be so neat.

@markweitzman Just as the link says, the **Risch algorithm** is a method of** indefinite integration** used in some computer algebra systems to find **antiderivatives**. In many cases, definite and indefinite integrals are not the same difficulty. You might think they're related because of the Newton-Leibniz formula. The following link is worth looking at, although the topic of discussion is Mathematica's integration problem.

https://mathematica.stackexchange.com/questions/204191/a-discontinuity-in-an-integral

@mmcdara Thank you, I learned a lot of skills from your codes, although the effect seems not so good in the new version according to your approach, as shown in the following picture.

Maybe we can change the code to do something like this, maybe it looks a little bit better.

@Carl Love The computer I have now only installed maple2020. It's late at night in my place, and I will run it on another computer with maple2021 installed as soon as possible tomorrow. maple2020 seems to be able to convert to latex and run your code well, but it is not displayed in the form of an array.

Another interesting thing is that when I run the code on this post, although many pictures in eps format are generated, an error occurs when I run the latex code.

https://www.mapleprimes.com/questions/228033-How-To-Solve-The--Unreasonable-Output