Introduction
Finding two numbers that multiply to a specific value and add to another specific value is a common problem in mathematics. This is particularly useful in understanding quadratic equations and solving real-world problems such as optimizing profits or analyzing statistical data.
Solving the Problem
To solve a problem where two numbers x and y multiply to -50 and add to 5, we can follow these steps:
Step 1: Set Up the Equations
Let the two numbers be x and y.
(x cdot y -50) (x y 5)Step 2: Express One Variable in Terms of the Other
We can express y in terms of x using the second equation:
gy 5 - xStep 3: Substitute and Simplify
Now substitute this expression for y into the first equation:
(x(5 - x) -50)
Expanding this equation gives:
(5x - x^2 -50)
Rearranging the equation leads to:
(x^2 - 5x - 50 0)
Step 4: Solve the Quadratic Equation
This is a quadratic equation in the form (ax^2 bx c 0), where (a 1), (b -5), and (c -50). We can solve this using the quadratic formula:
(x frac{{-b pm sqrt{b^2 - 4ac}}}{2a})
Substitute the values of (a), (b), and (c):
(x frac{5 pm sqrt{{(-5)^2 - 4 cdot 1 cdot (-50)}}}{2 cdot 1})
Distribute and simplify:
(x frac{5 pm sqrt{25 200}}{2})
(x frac{5 pm sqrt{225}}{2})
(x frac{5 pm 15}{2})
This gives us two solutions:
(x frac{20}{2} 10) (x frac{-10}{2} -5)Step 5: Find the Corresponding Value of the Other Variable
Substituting back to find y:
If (x 10), then (y 5 - 10 -5) If (x -5), then (y 5 - (-5) 10)Therefore, the two numbers are 10 and -5.
Verification
To verify, let's check if 10 and -5 satisfy both conditions:
10 (-5) 5 10 cdot (-5) -50Conclusion
The two numbers that multiply to -50 and add to 5 are 10 and -5. This problem can be solved systematically by setting up equations and using the quadratic formula, making it a valuable tool in algebraic problem-solving.