SOLUTION: Please help me solve: Find f(k-1) when f(x) = 4x^2 - 3x + 7

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Question 991885: Please help me solve: Find f(k-1) when f(x) = 4x^2 - 3x + 7
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
f(x) = 4x^2 - 3x + 7

f(k-1) = 4(k-1)^2 - 3(k-1) + 7

you just replace x with (k-1).

the rest is just simplification.

(k-1)^2 = k^2 - 2k + 1

the equation becomes:

f(k-1) = 4(k^2 - 2k + 1) - 3(k-1) + 7

simplify to get:

f(k-1) = 4k^2 - 8k + 4 - 3k + 3 + 7

combine like terms to get:

f(k-1) = 4k^2 - 11k + 14.

that's your solution.

i verified that's it's true.
i did it by making x = 5 and then evaluating the original equation.
i then made k = 6 and evaluated the final equation.
the answers were the same which confirms the solution is correct.