Question

The function f(x) varies directly with x and f(x)=90 when x = 30. What is f(x) when x = 6?

Answer 1

Answer: just took the test f(x) = 18

Step-by-step explanation:

Answer 2

Answer:

f(x)=18

Step-by-step explanation:

We are given that $f(x) \propto x$

So, $f(x) = kx$ ---1

Where k is the constant of proportionality

f(x)=90 when x = 30

Substitute the values in Equation 1

$90 = k(30)$

$3 = k$

So, equation becomes : $f(x) = 3x$

Now find f(x) when x = 6

Substitute x = 6 in equation 2

$f(x) = 3(6)$

$f(x) = 18$

Hence f(x)=18 when x = 6