Question

solve this sum fast please

Answer 1

Answer:

7 years

Step-by-step explanation:

let his present age is x years

so 3 years ago his age was x-3 years

and 5 years later his age will be x+5 years

now sum of the reciprocals of his age = 1/3

therefore, 1/(x-3) + 1/(x+5) = 1/3

take LCM of LHS

(x-3+x+5)/(x-3)(x+5) = 1/3

(2x+2)/(x²+2x-15) = 1/3

cross multiplying

3(2x+2) = x²+2x-15

6x+6 = x²+2x-15

x²-4x-21 = 0

splitting the middle term

x²+3x-7x-21 = 0

x(x+3)-7(x+3) = 0

(x+3)(x-7) = 0

x= -3, 7

but age can't be negative

therefore present age of rehman is 7 years