We know what the function does with the input so, just replace all x variables with 9.
[tex]f(9) = 6(9)^2 + 1(9) + 3 \\ \\ f(9) = 6(81) + 1(9) + 3 \\ \\ f(9) = 486 + 1(9) + 3 \\ \\ f(9) = 486 + 9 + 3 \\ \\ f(9) = 495 + 3 \\ \\ f(9) = 498 [/tex]
So, when we input 9 into the function we get 498. f(9) = 498.
