f(8) if f(x) = x + 11

Question

i need help am so confused on how to do it

 

Answer 1

f(x) = x + 11  MEANS "there's a function named f" that gives you a y-value when you plug any (legal) x value into the right side.

 

Example:  let x = 1   then  f(1) = 1 + 11 = 12   so on the graph of "f" you'll put the point that has coordinates (1,12).

 

Now in your specific case, they want f(8) = 8 + 11 = 19.  See how we substituted 8 on for x on right side?

 

It just a procedure, and learning it is vital.  Practice until you understand well because this part of Algebra occurs over & over in EVERY math class from here on.

Answer 2

Chileshe, you simply replace every x for what is inside the parentheses.

 

f(x) = x + 11

f(8) = 8 + 11 = 19

 

You can play around with it.

 

f(2) = 2 + 11 = 13

 

Hope this helps!