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sanjeev

· started a discussion

· 1 Months ago

what type of solution is this?? Ask yourself and please improve

Question:

Suppose y varies as the sum of two quantities of which one varies directly as x and the other inversely as x. If y = 6 when x = 4 and y = \(3\cfrac{1}{3}\)  when x = 3, then the relation between x and y is:

Options:
A) x = y + 4 
B) y = 2x + \(\cfrac{8}{x}\)
C) y = 2x - \(\cfrac{8}{x}\)
D) y = 2x - \(\cfrac{4}{x}\)
Solution:
Let relation be y=ax+\(\frac{b}{x}\)

given y=6 if x=4

6= 4a+\(\frac{b}{4}\)

or 16a+b =24.........(1)

again, y = 3\({1 \over3}\) if x=3

then, \(\frac{10}{3}\)=3a+\(\frac{b}{3}\)

or, 9a+b=10............(2)

on solving eqn (1)and(2)

a=2 and b=-8

then required relation-

y= 2x-\(\frac{8}{x}\)

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