Question

assume that y varies inversly with the square of x then solve when x is 5, y is 4/5 find y when x is 8

Answer 1

since y varies inversly with the square of x, it can be written like this

$y=\frac{k}{x^2}$

since y=4/5 when x=5, find k

$\frac{4}{5}=\frac{k}{(5^2)}$

clear the equation for k

$\begin{gathered} \frac{4}{5}(5^2)=k \\ 4\cdot5=k \\ 20=k \end{gathered}$

now that you have found k, use it to find y when x=8

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