Y is directly proportional to the square root of x
if y = 42 when x = 9 find,
x when y = 28

Given:

y is directly proportional to the square root of x.

y = 42 when x = 9

To find:

x when y = 28.

Solution:

We have,

y is directly proportional to the square root of x.

       ...(i)

where, k is the constant of proportionality.

We have, y = 42 when x = 9.

Putting k=14 in (i), we get

Putting y=28, we get

Taking square on both sides.

Therefore, the value of x is 4 when y=28.

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