011-40705070  or  
Call me
Download our Mobile App
Select Board & Class
  • Select Board
  • Select Class
Mani Rastogi from D, asked a question
Subject: Math , asked on 18/11/12

 The sum of ages of a father & his son is45. 5 years ago, the product of their ages was 124. Determine their present age.

EXPERT ANSWER

Mayank , Meritnation Expert added an answer, on 19/11/12

This conversation is already closed by Expert

  • Was this answer helpful?
  • 0
View More
Robin , added an answer, on 18/11/12
119 helpful votes in Math

present age

let age of son be x

let age of father be y

x + y = 45

y = 45 - x

so age of father can also be taken as y = 45 - x

age after 5 years

father's age = y + 5 = 45 - x + 5 = 50 -x

son's age = x + 5

( x + 5 ) ( 50 - x ) = 124

45x - x2 + 250  = 124

45x - x2 - 76 = 0

-x2 + 45x - 126 = 0

dividing the equation by -1 to make x2 positive

x2  - 45x + 126 = 0

sum = -45, product = 126

x2 - 3x - 42x + 126 = 0

x ( x - 3 ) -42 ( x - 3 ) = 0

( x - 3 ) ( x - 42 ) = 0

x = 3, 42

age of son = x = 3

age of father = y = 45 - x = 45 - 3 = 42

  • Was this answer helpful?
  • 0