manalq8 wrote:

What is the minimal value of function f(x)?

(1) f(0) = 16

(2) f(x) = (x – 4)2

What a strange question. Statement 1 is clearly not sufficient, since you only know about one value of the function. Statement 2 is certainly sufficient, since you know the exact definition of the function, so you can answer any question about it. There's no need to do any work.

And while you don't need to do any calculation here, the minimum value would be 0 if, as I assume, you mean Statement 2 to read:

f(x) = (x-4)^2

Then when x=4, f(x) = 0. The value of f(x) cannot be negative since it is a square.

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