Let y vary partly as 1/x and partly as x. When x = 1, y = 5 and when x = 4, y =25/2. Find y when x = 2. A.5/2 B. 4 C.25/4 D. 7 E.17/2

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aruv | High School Teacher | (Level 2) Valedictorian

Posted on

Let

`y=k/(x)+(mx)`

because y is partially proportional to (1/x) and x . k amd m are proportionality constants.

By given conditions.

`5=k+m`

`25/2=k/4+4m`

solving above system of equations in m and k ,we have

m=3 and k=2

Thus

y=2/x+(3x)

when  x=2 then

y=2/2+(3x2)=7

Correct choice for answer is D 

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