Correct Answer - Option 4 : 5
Given: The sum of a non zero number and twenty times its reciprocal is 9
Calculation: Let the non zero number be x.
And its reciprocal is 1/x.
⇒ x + 20/x = 9
⇒ x2 - 9x + 20 = 0
⇒ x2 - 5x - 4x + 20 = 0
⇒ x (x - 5) - 4 (x - 5) = 0
⇒ (x - 4) (x - 5) = 0
Now put x = 5
⇒ ( 5 )2 - 9 ( 5 ) + 20 = 0
⇒ 25 - 45 + 20 = 0
This satisfies the equation so the required number is 5
