Question

If y varies inversely as x^2 and y = 3 when x = 18, what is y when x = 3?a. 6 b .108 c.54 d.27 Please select the best answer from the choices provided ABCD

Answer 1

It is given in the question that

y varies inversely as x^2 and y = 3 when x = 18.

SInce y varies inversely as square of x, so the formula will be

`y = (k)/(x^2)`

Where k is the constant of proportionality .

Substituting the values of y and x, we will get

`3 = (k)/(18^2)`

`3 = (k)/(324)`

Multiplying both sides by 324,

`k = 972`

So the equation will be

`y= (972)/(x^2)`

And when x equals 3, we will get

`y = (972)/(9) = 108`

Therefore the correct option is B .