SOLUTION: How do you work out this worded problem? A father’s age is the square of his son’s age (x). In 20 years’ time the father will be 3 times as old as his son. What are the ages of the

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: How do you work out this worded problem? A father’s age is the square of his son’s age (x). In 20 years’ time the father will be 3 times as old as his son. What are the ages of the      Log On


   



Question 773656: How do you work out this worded problem? A father’s age is the square of his son’s age (x). In 20 years’ time the father will be 3 times as old as his son. What are the ages of the father and son? Thanks a lot
Answer by ramkikk66(644) About Me  (Show Source):
You can put this solution on YOUR website!
Let son's age be x
Father's age is x^2
In 20 years, son's age = x + 20
Father's age = x^2 + 20
The second statement can be expressed as
x%5E2+%2B+20+=+3%2A%28x+%2B+20%29+=+3%2Ax+%2B+60
x%5E2+-+3%2Ax+-+40+=+0
This is a quadratic equation which can be solved through factorization.
x%5E2+-+8%2Ax+%2B+5%2Ax+-+40+=+0
x%2A%28x+-+8%29+-+5%2A%28x+-+8%29+=+0
%28x+-+8%29%2A%28x+%2B+5%29+=+0
So the 2 solutions are
x - 8 = 0, or x = 8
x + 5 = 0, or x = -5
Since age has to be positive, the son's age is highlight%288%29 and therefore
the father's age is highlight%2864%29.
In 20 years age, son's age will be 28 and father's age will be 84.
28*3 = 84 (correct!)
:)