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Given that y varies inversely as the square of ... - WAEC Mathematics 2018 Question

Given that y varies inversely as the square of x. If x = 3 when y = 100, find the equation connecting x and y.

A
\(yx^2 = 300\)
B
\(yx^2 = 900\)
C
y = \(\frac{100x}{9}\)
D
\(y = 900x^2\)
correct option: b

Y \(\alpha \frac{1}{x^2} \rightarrow y = \frac{k}{x^2}\)

If x = 3 and y = 100,

then, \(\frac{100}{1} = \frac{k}{3^2}\)

\(\frac{100}{1} = \frac{k}{9}\)

k = 100 x 9 = 900

Substitute 900 for k in

y = \(\frac{k}{x^2}\); y = \(\frac{900}{x^2}\)

= \(yx^2 = 900\)

 

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