Question

can someone help me with the steps of this so I can understand it better?
If f(x) varies directly with x and f(x) = 2 when x = 10, then what is the value of f(x) when x = 40?
(Points : 4)
8
45
200
320

Answer 1

"f(x) varies directly with x" which means

f(x) = k*x

where k is some constant

Answer 2

we are told that " f(x) = 2 when x = 10", so plug these two values in and then solve for k

f(x) = k*x

10 = k*2

10/2 = k

5 = k

k = 5

Answer 3

That means our equation goes from f(x) = k*x to f(x) = 5x

Answer 4

Do you see how to finish up?

Answer 5

ok then would I divide f(x) to x to get the k?

Answer 6

exactly

Answer 7

once you figure out k, you plug in x = 40 into f(x) = 5x to get your final answer

Answer 8

ok that makes sense

Answer 9

thank you

Answer 10

sure thing