To evaluate a function at a given input, you have to substitute every occurrence of the variable with that particular value.
So, for the first function, you have

The name of the variable is obviously irrelelvant, so the same goes for the second function:

I think its runner B because its lower down then runner A hope this helps
Answer:
see below
Step-by-step explanation:
As with many multiple-choice questions, the appropriate choices can often be determined with a simple test. Here, you only need to look at the values of the constants. (Those are ringed in blue.)
So hmmm x²+6x+8=0
alrite.. let's do some grouping now
( x² + 6x + [?]²) + 8 = 0
notice above, we have a missing fellow in order to get a perfect square trinomial... hmm who would that be?
let's take a peek at the middle guy of the trinomial.. 6x.. hmmm let's factor it, 2*3*x, wait a minute! 2 * 3 * x... we already have x² on the left-side, since the middle term is just 2 * the square root of the other two terms, that means that the guy on the right, our missing guy must be "3"
alrite, let's add 3² then, however, bear in mind that, all we're doing is borrowing from our very good friend Mr Zero, 0
so if we add 3², we also have to subtract 3², let's do so
(x² + 6x +3² - 3²) + 8 = 0
(x² + 6x +3²) + 8 - 3² = 0
(x+3)²=3² - 8
(x+3)² = 1