The sum of a certain number and its reciprocal is equal to 2,9. What is the absolute value of the difference of this number and its reciprocal ?	Select
A) 2,2  B) 1,2  C) 0,3  D) 0,4  E) 2,1
x + 1/x = 2.9   x-1/x = y   Add two equations   2x = 2.9 + y   So when 2.9 and correct answer choice are added, the final digit should be even   So eliminate A, B and D   Substitute y=0.3   x=1.6   1.6+1/1.6 is not equal to 2.9   Substitute y = 2.1   So x=2.5   2.5+1/2.5= 
<gadget id="calculator">2.5+1/2.5</gadget>
<output>2.9</output>
2.9   ANSW2,1R:2,1
<result>E</result>
The sum of a certain number and its reciprocal is equal to 2,9. What is the absolute value of the difference of this number and its reciprocal ?