I want to insert say "x^2 + 2x", and then I want a way to simply change the value of x (x=3, x=-1, etc) and get the result. How can I achieve this?
I'm trying these ways but they don't work:
https://imgur.com/a/KnZS0yB
x^2 + 2x , x = 3
(3)^2 + 2(3) =
9 + 6 =
15