Question

Which equation is the direct variation equation if f(x) varies directly with x and f(x)=-2 when x=6

Question 3 options:

f (x)=- 2 x


f (x )=-1 /2 x


f (x )=-6 x


f (x )= -18 x

Answer 1

`f(x)=-x/3`

Explanation

Given f is a direct variation equation (Direct variation is when one variable is equal to a constant times another variable, with no additions or subtractions alongside).

Now by the above condition let the constant be "c".Then

`f(x)=cx`

also given that
`f(x)=-2` when
`x=6`

on substituting the above values,

`-2=c(6)`

`c=-2/6`

`c=-1/3`

Therefore our equation is
`f(x)=-x/3`