Answer :
this is simple multiplication
do 2*4 and 10*4
so you get f(x)=8 and x=40
if you wanna do it by doing division do
2=10
f(x)=40
cross multiply then divide
so do 2*40 to get 80
then do 80/10 to get 8
do 2*4 and 10*4
so you get f(x)=8 and x=40
if you wanna do it by doing division do
2=10
f(x)=40
cross multiply then divide
so do 2*40 to get 80
then do 80/10 to get 8
Answer: a.8
Step-by-step explanation:
Given : If f(x) varies directly with x and f(x) = 2 when x = 10
We know if two quantities (x and f(x)) are directly proportional then
[tex]\frac{x_1}{f(x_1)}=\frac{x_2}{f(x_2)}[/tex]
Now, for the given problem we have ,
[tex]\frac{10}{2}=\frac{40}{f(40)}\\\\\Rightarrow\ f(40)=\frac{40\times2}{10}\\\\\Rightarrow\ f(40)=8[/tex]
Hence, if x = 40, then f(x)=8.
