Question

Y is directly proportional to the positive square root of (x+2)when x=7,y=9. Find y when x=23

Answer 1

15

Explanation:

Given: y is directly proportional to
`√(x+2)` when x = 7, y = 9

To find: y when x = 23

Solution:

u and v are said to be proportional if
`u=kv` where k is a constant of proportionality.

As y is directly proportional to
`√(x+2)` when x = 7, y = 9,

`y=k√(x+2)\\`

Put x = 7, y = 9

`9=k√(7+2)=3k\\ k=(9)/(3)=3\\ y=3√(x+2)`

Put x = 23

`y=3√(23+2)=3√(25)=3(5)=15`