This is even easier to see if you remember that summation is discrete integration, which is the opposite of differentiation, which reduces degree by one. I recommend Graham, Knuth and Patashnik’s “Concrete Mathematics” for stuff like this.
This is even easier to see if you remember that summation is discrete integration, which is the opposite of differentiation, which reduces degree by one. I recommend Graham, Knuth and Patashnik’s “Concrete Mathematics” for stuff like this.