Answer:
Option a - f(x)=20x
Step-by-step explanation:
Given : For a certain function f = f(x), we know that f is proportional to x and that the constant of proportionality is 20.
To Find : A formula for f ?
Solution :
We have given that,
f is proportional to x i.e. [tex]f\propto x[/tex]
This implies [tex]f=kx[/tex]
Where, k is the proportionality constant
The constant of proportionality is 20.
So, [tex]f=20x[/tex]
On comparing with, f = f(x)
[tex]f=f(x)=20x[/tex]
Therefore, The formula of f is [tex]f=f(x)=20x[/tex]
So, Option a is correct.