Math Problem Statement

Find two number the have a sum of 23 and a product of 120

Solution

Let's denote the two numbers as xx and yy.

We are given the following conditions:

x+y=23x + y = 23 x×y=120x \times y = 120

To find xx and yy, we can solve this system of equations.

First, express yy in terms of xx using the first equation:

y=23xy = 23 - x

Substitute this into the second equation:

x×(23x)=120x \times (23 - x) = 120

This expands to:

23xx2=12023x - x^2 = 120

Rearrange the equation into a standard quadratic form:

x223x+120=0x^2 - 23x + 120 = 0

Now, we solve this quadratic equation using the quadratic formula:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

For our equation x223x+120=0x^2 - 23x + 120 = 0, the coefficients are a=1a = 1, b=23b = -23, and c=120c = 120. Plugging these into the quadratic formula:

x=(23)±(23)24(1)(120)2(1)x = \frac{-(-23) \pm \sqrt{(-23)^2 - 4(1)(120)}}{2(1)}

x=23±5294802x = \frac{23 \pm \sqrt{529 - 480}}{2}

x=23±492x = \frac{23 \pm \sqrt{49}}{2}

x=23±72x = \frac{23 \pm 7}{2}

This gives us two possible values for xx:

x=23+72=15orx=2372=8x = \frac{23 + 7}{2} = 15 \quad \text{or} \quad x = \frac{23 - 7}{2} = 8

Thus, the two numbers are 1515 and 88.

Let's verify:

  • Their sum: 15+8=2315 + 8 = 23
  • Their product: 15×8=12015 \times 8 = 120

Both conditions are satisfied, so the two numbers are 15 and 8\boxed{15 \text{ and } 8}.

Would you like more details on the solution or have any other questions?


Here are five related questions to expand on this topic:

  1. How can you solve a system of linear and quadratic equations?
  2. What are the different methods to solve a quadratic equation?
  3. Can you always factorize a quadratic equation?
  4. What is the significance of the discriminant in the quadratic formula?
  5. How do you solve a quadratic equation when the discriminant is negative?

Tip: When solving quadratic equations, always check if the equation can be factored easily before using the quadratic formula. This can save time and simplify the process.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
System of Equations

Formulas

Quadratic formula

Theorems

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Suitable Grade Level

Grades 9-12