If \(y \propto \frac{1}{x^2}\) and x = 3 when y = 4, find y when x = 2.
- 1
- 3
-
9
- 18
- 21
The correct answer is: C
Explanation
\(y \propto \frac{1}{x^2}\)
\(y = \frac{k}{x^2}\)
\(4 = \frac{k}{3^2}\)
\(k = 4 \times 3^2 = 36\)
\(y = \frac{36}{x^2}\)
When x = 2,
\(y = \frac{36}{2^2} = 9\)