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Nastasia [14]
3 years ago
5

If y varies inversely as x, and y=10 when x=2, find y when x=8

Mathematics
2 answers:
snow_lady [41]3 years ago
5 0
If it varies inversely, then their product is the same. So,
10*2 = y*8
20 = y*8
 /8      /8
5/2 = y
y = 2.5
dedylja [7]3 years ago
4 0
\bf \qquad \qquad \textit{inverse proportional variation}\\\\
\textit{\underline{y} varies inversely with \underline{x}}\qquad \qquad  y=\cfrac{k}{x}\impliedby 
\begin{array}{llll}
k=constant\ of\\
\qquad  variation
\end{array}\\\\
-------------------------------\\\\
\textit{we also know that }
\begin{cases}
y=10\\
x=2
\end{cases}\implies 10=k2\implies \cfrac{10}{2}=k\implies 5=k
\\\\\\
therefore\qquad \boxed{y=\cfrac{5}{x}}
\\\\\\
\textit{when x = 8, what is \underline{y}?}\qquad y=\cfrac{5}{8}
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