During the factorization process from the point of view of a function, I have difficulty to see where some part gets converted.
Assuming we have the function
When I want to evaluate as...
Taken from my course textbook outlining this process to replace all $x$ to $a+h$.
The simplification procedure seems unclear to me:
$$f(a+h) = 2(a+h)^2+3(a+h)-1$$ $$f(a+h) = 2(a^2+2ah+h^2)+3(a+h)-1$$ $$f(a+h) = 2a^2+4ah+2h^2+3a+3h-1$$
The second line where Mostly when ... $2ah$ ... gets me confused.
What could be the explanation?