Question

The sum of Rehman's age reciprocal (in years) 3years ago & 5years from now is 1/3. Find his present age .
Maths Genius buddies plz answer... I need it for my tomorrow's SSC exam..!!!​

Answer 1

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let present age of rahaman is x yrs

3 yrs ago age of rahman was x-3 yrs

5 yrs from now age of rahman will be x+5 yrs

As per given conditions ,

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

by LCM

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

=2x+2/x^2 +2x -15 =1/3

by cross multiplication we can find

6x+6 =x^2 +2x-15

x^2+2x -15 -6x -6 =0

x^2 -4x-21=0

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

x-7=0 or x=3 =0

x=7 or x=-3

Rahman's present age is 7 yrs .

Answer 2

Answer:

7 Years

Step-by-step explanation:

The sum of Rehman's age reciprocal (in years) 3years ago & 5years from now is 1/3. Find his present age .  

Maths Genius buddies plz answer... I need it for my tomorrow's SSC exam..!!!​

Let say Rehman current Age = R Years

Age three year before = R-3 Years

Reciprocal of age 3 years before = 1/(R-3)

Age after 5 year = R + 5 Years

Reciprocal of age after 5 years = 1/(R+5)

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

multiplying both sides by 3(R-3)(R+5)

=> 3(R + 5) + 3(R-3) = (R-3)(R+5)

=> 3R + 15 + 3R - 9 = R² - 3R + 5R - 15

=> R² - 4R -21= 0

=> R² - 7R + 3R - 21 = 0

=> R(R-7) + 3(R-7) = 0

=> (R+3)(R-7) = 0

=> R = 7    ( R = -3 not possible as age can not be -ve)

So current Age = 7 Years

Verification :

age 3 year befor = 4 Year after  5 years = 12 Years

1/4 + 1/12 = (3 +1)/12 = 4/12 = 1/3