SOLUTION: Present age of a father is three years less than two times the square of his son's age. Difference of their ages is 42 years, what are their present ages.

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: Present age of a father is three years less than two times the square of his son's age. Difference of their ages is 42 years, what are their present ages.      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 771442: Present age of a father is three years less than two times the square of his son's age. Difference of their ages is 42 years, what are their present ages.
Answer by Jc0110(165) About Me  (Show Source):
You can put this solution on YOUR website!
Let the age of father to be x while of son to be y.
x=2y%5E2-3 --> Equation 1
x-y=42
x=42%2By --> Equation 2 ... Substitute x=42%2By into Equation 1.
42%2By=2y%5E2-3
0=2y%5E2-y-3-42
0=2y%5E2-y-45
2y%5E2-y-45=0
%282y%2B9%29%28y-5%29=0
y=-9%2F2 or y=5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
y=-9%2F2 is not accepted as answer because the age of a person can't be in negative.
while
y=5 is accepted as answer.
When y=5, ... Substitute y=5 into Equation 2
x=42%2B5
x=47
Therefore, the age of father is 47 while of son is 5.