Respuesta :

Given the following variation

[tex]Q\propto\frac{1}{(b+R)^2}[/tex]

Introducing the constant of proportionality c as shown below

[tex]\begin{gathered} Q=c\times\frac{1}{(b+R)^2} \\ Q=\frac{c}{(b+R)^2} \end{gathered}[/tex]

Q=4, when b=2, R= 8

Let use the above values of Q, b, and R to find the value of c as shown below:

[tex]\begin{gathered} 4=\frac{c}{(2+8)^2} \\ 4=\frac{c}{10^2} \\ 4=\frac{c}{100} \\ c=4\times100 \\ c=400 \end{gathered}[/tex]

Let us substitute c in the formula as shown below

[tex]Q=\frac{400}{(b+R)^2}[/tex]

Hence, the specific formula to describe the variation is

Q= 400/(b+R)²