The sum of a positive number and its reciprocal is thrice the difference of the number and its reciprocal. The number is :
A. $$\sqrt 2 $$
B. $$\frac{1}{{\sqrt 2 }}$$
C. $$\sqrt 3 $$
D. $$\frac{1}{{\sqrt 3 }}$$
Answer: Option A
Solution(By Examveda Team)
Let the number be xThen,
$$\eqalign{ & \Leftrightarrow x + \frac{1}{x} = 3\left( {x - \frac{1}{x}} \right) \cr & \Leftrightarrow \frac{{{x^2} + 1}}{x} = 3\left( {\frac{{{x^2} - 1}}{x}} \right) \cr & \Leftrightarrow {x^2} + 1 = 3{x^2} - 3 \cr & \Leftrightarrow 2{x^2} = 4 \cr & \Leftrightarrow {x^2} = 2 \cr & \Leftrightarrow x = \sqrt 2 \cr} $$
Related Questions on Problems on Numbers
If one-third of one-fourth of a number is 15, then three-tenth of that number is:
A. 35
B. 36
C. 45
D. 54
E. None of these
A. 9
B. 11
C. 13
D. 15
E. None of these
A. 3
B. 4
C. 9
D. Cannot be determined
E. None of these
Join The Discussion