Question

If from a positive number, twice its reciprocal is subtracted, we get 1. Then the number is ___. 4 3 1 2

Solution

The correct option is D 2 Suppose the number be x According to the given condition x−2x=1 x2−2=x x2−x−2=0 Using quadratic formula, x=−b±√b2−4ac2a Here, a=1,b=−1 and c=−2 ⇒x=1±√1+82          =1±32 ⇒x=2 or−1 As the number is positive, ignore negative value. Hence, x = 2 ​∴ The required number is 2.

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