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 4 of 6.
Stephen said:
6 years ago
If the fraction is 4/5.
Then 4/5(fraction)-5/4(reciprocal) = -9/20.
So, I believed the answer(fraction) = 5/4.
Then 4/5(fraction)-5/4(reciprocal) = -9/20.
So, I believed the answer(fraction) = 5/4.
Gagan said:
1 decade ago
Wrong. Why did you take the resiprocal first why not the fraction which was mention first in the question?
Sonali said:
1 decade ago
I can't understand this step.
20x^2+25x-16x-20=0.
How it becomes 25x & 16x ?
Please explain.
20x^2+25x-16x-20=0.
How it becomes 25x & 16x ?
Please explain.
Narasingarao said:
1 decade ago
What is meant by reciprocal and positive proper fraction? concept not cleared kindly help.
Tobzs said:
6 years ago
4+5=9
4 * 5 = 20,
And 9/20 = 4/5 in the simplified form
So, 4/5 is the answer.
4 * 5 = 20,
And 9/20 = 4/5 in the simplified form
So, 4/5 is the answer.
Ashutosh rusiya said:
4 years ago
Take x is a fraction number and 1/x would be its reciprocal number and x-1/x =9/20.
(2)
Janu said:
1 decade ago
Ofcourse if we take x-(1/x)=(9/20)
then x will be 5/4 which is not in the options
then x will be 5/4 which is not in the options
Rani said:
1 decade ago
(4x + 5)(5x - 4) = 0.
4x + 5 = 5x - 4.
(5x-4x)+ 5 = 4.
x+5 = 4.
x = 4/5.
4x + 5 = 5x - 4.
(5x-4x)+ 5 = 4.
x+5 = 4.
x = 4/5.
Chetan said:
1 decade ago
How did you get (4x+5)(5x-4)=0 as x=4/5? Could you please explain?
Sakshi sharma said:
6 years ago
Why have we taken the fraction as 1/x? what if we take it as a/b?
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