Consider the function represented by 9x + 3y = 12 with x as the independent variable. How can this function be written using function notation?

Question

I have tried to solve this problem more the three times and still can not figure it out can someone please help me? 

Answer 1

So, Luna, in a function, f(x) and y are interchangeable. First, we need to solve for y.

 

9x + 3y = 12

-9x           -9x

3y = -9x + 12

3          3

y = -3x + 4

 

f(x) = -3x + 4

 

From here, you can find, say f(9).

 

f(9) = -3(9) + 4 = -27 + 4 = -23

 

Hope this helps!