SOLUTION: Please respond by 9:00 am tomorrow because I must know before my finals, and let me thank you for helping me beforehand! Question: f(x)=16-2/3x ; Find f(-6). I have tried solving

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Question 1105163: Please respond by 9:00 am tomorrow because I must know before my finals, and let me thank you for helping me beforehand! Question:
f(x)=16-2/3x ; Find f(-6).
I have tried solving this problem by substituting x for -6 like so:
f(x)=16-2/3(-6). My final answer was f(x)=12. My teacher gave me the correct answer but I can't seem to get her answer. Teacher's answer: f(-6)=20
Please let me know as soon as possible how to solve this problem because I would appreciate it.
From AlgebraGirl003
Found 3 solutions by ikleyn, jim_thompson5910, josgarithmetic:
Answer by ikleyn(52776)   (Show Source): You can put this solution on YOUR website!
.
f(-6) = 16 -  = 16 +  = 16 + 2*2 = 16 + 4 = 20.


Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

f(x) = 16 - 2/3x should be written as f(x) = 16 - (2/3)*x
the change here is the 2/3 is surrounded in parenthesis. This is so it's clear that we're multiplying 2/3 by x

Replace every x with -6
f(x) = 16 - (2/3)*x
f(-6) = 16 - (2/3)*(-6)

Now multiply 2/3 with -6. Think of -6 as -6/1
So we really have (2/3) times (-6/1)
Multiplying fractions will have us multiply straight across


So after the multiplication step, we go from this
f(-6) = 16 - (2/3)*(-6)
to this
f(-6) = 16 - (-4)
which turns into this
f(-6) = 16 + 4
f(-6) = 20

Let me know if that clears things up or not. Thank you.
Answer by josgarithmetic(39616)   (Show Source): You can put this solution on YOUR website!
This is for simple substitution and evaluating the expression.

You really have this function:
Put the parentheses in the correct places just to make that clear.

You want f when x=-6.




Maybe you figure out the last step.
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