# X varies inversely as the square of y, and x=3 when y=20, what is the equation?

Jul 23, 2017

The equation is $x \cdot {y}^{2} = 1200$

#### Explanation:

 x prop 1/y^2 or x = k * 1/y^2 or x * y^2 = k ; k  is constant of

proportionality.  x =3 , y = 20 ; then , $3 \cdot {20}^{2} = k \mathmr{and} k = 1200$

$\therefore x \cdot {y}^{2} = 1200$

Hence the equation is $x \cdot {y}^{2} = 1200$ [Ans]