The multiplication of the age of Rajiv, before 5 years and after 9 years, is 15 :

The multiplication of the age of Rajiv, before 5 years and after 9 years, is 15. What is the present age of Rajiv ?
(a) 6
(b) 7
(c) 5
(d) 8

Anurag Mishra Professor Asked on 10th February 2016 in Maths.
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1 Answer(s)

Answer: (a) 6

Solution:-
Let the present age of Rajiv be X years

The multiplication of the age of Rajiv, before 5 years and after 9 years.
Then, (X – 5) (X + 9) = 15
X2 + 9 X – 5X – 45 = 15
X2 + 4 X – 45 – 15 =0
X2 + 4 X – 60 = 0
X2  + 10 X – 6 X – 60 = 0
X (X + 10 ) – 6 (X + 10) = 0
(X – 6) (X + 10) = 0
X – 6 = 0
X = 6

Then, the present age of Rajiv is 6 years.

Hence, the correct answer is option (a) 6 years.

Anurag Mishra Professor Answered on 10th February 2016.
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