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How do you evaluate f(x)=3×3-4x+5

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-- It'll be a lot easier if you clean up the function first.
You're not changing the function. You're just making it
easier to read and work on without mistakes.

Notice that 3x3=9 , so the function is f(x) = 9 - 4x + 5

Combine like terms, and the function is f(x) = 14 - 4x .
Much easier to work with.

-- Now, when somebody tells you to evaluate the function for some number,
just take their number, write it in place of 'x',and see what you've got.

Example:

f(x) = 14 - 4x

Evaluate f(x) for x = 3.

-- Write 3 in place of 'x' in the function: f(3) = 14 - 4(3)

-- 4(3) = 12 . So the function is f(3) = 14 - 12

-- Finish up the subtraction : f(3) = 2

You just evaluated f(x) for x=3.
Nice job !


User Morido
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