P(n, r) = n!
____
(n-r)!
= 8!
____
(8-1)!
= 8
F(6) says “take f(x) = -4x + 11 and put 6 in for every x-value and then clean it up.”
f(6) = -4(6) + 11
= -24 + 11
= -13
f(x) = -1 says “set your function equal to -1 and solve for x”
f(x) = -1
-4x+11 = -1
-4x = -12
x = 3
So f(3) = -1.