Sum and Product of Two Numbers
Given two numbers a and b, their sum (a + b) and product (a x b) are the most fundamental operations in arithmetic. These operations are commutative, meaning the order does not matter. Additionally, knowing the sum and product of two numbers uniquely determines the numbers themselves (up to order) via Vieta's formulas.
Key Formulas
Sum
The result of adding two numbers together.
S = a + b
Product
The result of multiplying two numbers together.
P = a x b
Reverse: Find a and b
Given S and P, solve the quadratic x^2 - Sx + P = 0.
x = (S +/- sqrt(S^2 - 4P)) / 2
Difference of Squares
Relates sum, difference, and product of two expressions.
(a+b)(a-b) = a^2 - b^2
Applications
- Vieta's formulas connect roots of polynomials to their coefficients via sum and product.
- Factoring quadratic expressions requires finding two numbers with a given sum and product.
- Cryptographic algorithms rely on the difficulty of finding factors given a product.
- Statistics uses sum and product for mean, variance, and correlation calculations.