Understanding (a+b) x (c+d)
The expression (a+b) x (c+d) represents the multiplication of two binomial expressions. This type of multiplication is a fundamental concept in algebra and is frequently encountered in various mathematical contexts. Let's break down the process and explore its significance:
The Distributive Property
The core principle underlying the multiplication of binomials is the distributive property. This property states that multiplying a sum by a number is the same as multiplying each term of the sum by that number individually and then adding the results.
In the case of (a+b) x (c+d), we can apply the distributive property twice:

First distribution: We multiply the first term of the first binomial (a) by each term of the second binomial (c and d):
 a x c = ac
 a x d = ad

Second distribution: We then multiply the second term of the first binomial (b) by each term of the second binomial:
 b x c = bc
 b x d = bd
Combining the Results
Finally, we add all the individual products obtained from the distribution steps:
(a+b) x (c+d) = ac + ad + bc + bd
Example
Let's illustrate the process with an example:
Suppose a = 2, b = 3, c = 4, and d = 5.
(2+3) x (4+5) = (2 x 4) + (2 x 5) + (3 x 4) + (3 x 5)
= 8 + 10 + 12 + 15
= 45
Applications
The multiplication of binomials is essential in various mathematical areas, including:
 Algebraic manipulations: Simplifying and solving equations involving polynomials.
 Calculus: Finding derivatives and integrals of functions.
 Geometry: Calculating areas and volumes of geometric figures.
 Physics: Modeling physical phenomena and solving equations in physics.
Conclusion
Understanding the concept of multiplying binomials through the distributive property is crucial for proficiency in algebra and other related fields. The expanded form of (a+b) x (c+d) as ac + ad + bc + bd provides a structured approach to handling these expressions and facilitates further mathematical operations.