Question 822132
In function notation, the expression between the parentheses represents the input to the function. So in "f(x)" the expression between the parentheses, the x, represents the input to the function.<br>
And when you're given a formula for a function, like f(x) = x^2 + 1, the x still represents the input and the right side shows what the function will do with that input as it determines the output: It will square the input and add 1.<br>
So f(2) means: "Use 2 as the input to function f." And when we use the 2 as the input, the function will do what it does to all of its inputs: It will square the input and add 1. So:
f(2) = (2)^2 + 1 = 4 + 1 = 5<br>
It should now be clear that f(x), x^2+1, plus f(2), 5, will add up to x^2 + 6.