Expanding (a+b)(c+d): A Guide to FOIL and Distributive Property
The expression (a+b)(c+d) is a common algebraic expression that often arises in various mathematical contexts. Expanding this expression involves multiplying out the terms within the parentheses, and there are two primary methods for doing so: FOIL and the Distributive Property.
The FOIL Method
FOIL stands for First, Outer, Inner, Last. It's a mnemonic device for remembering the steps involved in multiplying binomials:
- First: Multiply the first terms of each binomial: a * c = ac
- Outer: Multiply the outer terms of the binomials: a * d = ad
- Inner: Multiply the inner terms of the binomials: b * c = bc
- Last: Multiply the last terms of each binomial: b * d = bd
Finally, add up all the resulting terms to get the expanded form: ac + ad + bc + bd.
The Distributive Property
The distributive property is a more general approach that applies to multiplying any number of terms. It states that: a(b+c) = ab + ac.
Applying this to our expression, we distribute the first binomial (a+b) over the terms of the second binomial (c+d):
- a(c+d) = ac + ad
- b(c+d) = bc + bd
Then, we add the two results together: ac + ad + bc + bd.
Summary
Both the FOIL method and the Distributive Property lead to the same expanded form: ac + ad + bc + bd. While FOIL provides a specific order to remember, the Distributive Property offers a more general and flexible approach for expanding expressions. Ultimately, the choice depends on personal preference and the complexity of the problem.