Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 26)
26.
The difference between a positive proper fraction and its reciprocal is 9/20. The fraction is:
Answer: Option
Explanation:
| Let the required fraction be x. Then | 1 | - x = | 9 |
| x | 20 |
 |
1 - x2 | = | 9 |
| x | 20 |
20 - 20x2 = 9x
20x2 + 9x - 20 = 0
20x2 + 25x - 16x - 20 = 0
5x(4x + 5) - 4(4x + 5) = 0
(4x + 5)(5x - 4) = 0
| x = | 4 |
| 5 |
Discussion:
53 comments Page 6 of 6.
Janu said:
1 decade ago
If we assume that the +ve fraction would be x
then x + (9/20) = 1/x (ex: x+y=z => y=z-x)
So (1/x) - x = (9/20)...
Hope you understand...
then x + (9/20) = 1/x (ex: x+y=z => y=z-x)
So (1/x) - x = (9/20)...
Hope you understand...
Chetan said:
1 decade ago
How did you get (4x+5)(5x-4)=0 as x=4/5? Could you please explain?
Gagan said:
1 decade ago
Wrong. Why did you take the resiprocal first why not the fraction which was mention first in the question?
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