Math Problem Statement

The sum of the ages of father and his son is 45 years .five years ago, the product of their ages in years was 124. Determine their present age .

Solution

Let's define the present age of the father as xx and the present age of the son as yy.

Step 1: Set up the equations

We are given two pieces of information:

  1. The sum of their ages is 45 years: x+y=45x + y = 45
  2. Five years ago, the product of their ages was 124: (x5)(y5)=124(x - 5)(y - 5) = 124

Step 2: Expand the second equation

Now, let's expand the second equation: (x5)(y5)=xy5x5y+25(x - 5)(y - 5) = xy - 5x - 5y + 25 Substitute x+y=45x + y = 45 into the equation: xy5(x+y)+25=124xy - 5(x + y) + 25 = 124 xy5(45)+25=124xy - 5(45) + 25 = 124 xy225+25=124xy - 225 + 25 = 124 xy200=124xy - 200 = 124 xy=324xy = 324

Step 3: Solve the system of equations

Now we have the system of equations: x+y=45x + y = 45 xy=324xy = 324

These equations form a system that can be solved using substitution or the quadratic formula.

We can express yy from the first equation: y=45xy = 45 - x Substitute this into the second equation: x(45x)=324x(45 - x) = 324 45xx2=32445x - x^2 = 324 Rearrange the equation: x245x+324=0x^2 - 45x + 324 = 0

Step 4: Solve the quadratic equation

Now, we solve the quadratic equation x245x+324=0x^2 - 45x + 324 = 0 using the quadratic formula: x=(45)±(45)24(1)(324)2(1)x = \frac{-(-45) \pm \sqrt{(-45)^2 - 4(1)(324)}}{2(1)} x=45±202512962x = \frac{45 \pm \sqrt{2025 - 1296}}{2} x=45±7292x = \frac{45 \pm \sqrt{729}}{2} x=45±272x = \frac{45 \pm 27}{2}

So, the two possible values for xx are: x=45+272=36orx=45272=9x = \frac{45 + 27}{2} = 36 \quad \text{or} \quad x = \frac{45 - 27}{2} = 9

Step 5: Determine the correct solution

If x=36x = 36, then from x+y=45x + y = 45, we get y=4536=9y = 45 - 36 = 9.

If x=9x = 9, then y=459=36y = 45 - 9 = 36.

Thus, the father is 36 years old and the son is 9 years old.

Final Answer:

  • The father is 36 years old.
  • The son is 9 years old.

Would you like further clarification on this solution?

Here are some related questions for you:

  1. How can you solve systems of equations involving quadratic expressions?
  2. What is the quadratic formula and how is it derived?
  3. How do you interpret word problems involving age-related relationships?
  4. What would happen if the sum of their ages were different?
  5. Can the product of their ages ever be negative?

Tip: Always double-check the signs when solving quadratic equations, especially in word problems!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Quadratic Equations

Formulas

x + y = 45
(x - 5)(y - 5) = 124
Quadratic equation formula: ax^2 + bx + c = 0

Theorems

Quadratic formula

Suitable Grade Level

Grades 7-9