Question

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Answer 1

is x >3 or is x≤3 for f(2)?

Answer 2

is x >3 or is x≤3 for f(2)?

Answer 3

when you are given f(x), and they ask for f(2) that is short hand for:
replace x with 2 and figure it out.

so if you have to figure out f(2)
is x >3 or is x≤3

Answer 4

yes. x is 2, so use the 2nd line to find f(2)
1/2x+1, if x≤3

I can't tell what that is:
\[ \frac{1}{2}x+1 \]
or
\[ \frac{1}{2x+1} \]
but whatever it is, replace the x with a 2, and do the arithmetic

Answer 5

yes, with x=5, use the first line
9*5-4= 45-4 = 41

Answer 6

I hope you got the idea. It isn't too tricky, just learning the shorthand...