When working with algebraic equations, the process of expanding and simplifying expressions is crucial for solving problems efficiently. One common operation in algebra is squaring a binomial, such as (A – B)^2, which involves multiplying the binomial by itself.

Expanding (A – B)^2 allows us to determine the product and simplify the resulting expression. To do this, we can use the concept of FOIL, which stands for First, Outer, Inner, Last. When we square a binomial, we are essentially multiplying it by itself, following this pattern.

Let’s break down the process step by step:

**First**: Multiply the first terms in each binomial. In this case, we have A * A = A^2.**Outer**: Multiply the outer terms of the binomials. This means multiplying the first term of the first binomial by the second term of the second binomial, which gives us A * -B = -AB.**Inner**: Multiply the inner terms of the binomials. Multiply the second term of the first binomial by the first term of the second binomial, resulting in -B * A = -BA.**Last**: Finally, multiply the last terms in each binomial. This gives us -B * -B = B^2.

Now, we put these results together:

(A – B)^2 = A^2 + (-AB) + (-BA) + B^2

Simplifying further:

(A – B)^2 = A^2 – AB – BA + B^2

(A – B)^2 = A^2 – 2AB + B^2

Therefore, the square of the binomial (A – B)^2 simplifies to **A^2 – 2AB + B^2**. This expression is useful in various algebraic manipulations and problem-solving situations.

### Applications of (A – B)^2:

Understanding how to expand and simplify expressions like (A – B)^2 is essential in algebra and mathematics in general. Here are some applications of this concept:

#### 1. **Quadratic Equations**:

- The expression (A – B)^2 frequently appears when dealing with quadratic equations and completing the square. It helps in factoring and solving equations efficiently.

#### 2. **Geometric Formulas**:

- In geometry, the expression (A – B)^2 can be used in formulas related to area, volume, and perimeter calculations of various shapes.

#### 3. **Physics Calculations**:

- Physics problems often involve manipulating expressions like (A – B)^2 to analyze relationships between variables, such as in equations of motion or energy calculations.

### FAQs (Frequently Asked Questions):

#### 1. What is the difference between (A – B)^2 and A^2 – B^2?

- The expression (A – B)^2 represents squaring the entire binomial (A – B), while A^2 – B^2 is the result of squaring each term individually and subtracting them.

#### 2. How do you expand (A + B)^2?

- To expand (A + B)^2, follow the same FOIL method but with plus signs: (A + B)^2 = A^2 + 2AB + B^2.

#### 3. Why do we use FOIL when expanding binomials?

- FOIL is a mnemonic for a specific order of multiplying binomials to ensure all terms are considered. It helps simplify the expansion process.

#### 4. Can you expand more complex expressions than (A – B)^2 using similar methods?

- Yes, the same principles of distributing and combining like terms apply to expanding higher-degree polynomials and more complex algebraic expressions.

#### 5. How can expanding (A – B)^2 be applied in real-life scenarios?

- Real-life applications of expanding (A – B)^2 can be found in fields like engineering, finance, and computer science, where algebraic manipulations are used to model and solve practical problems.

By mastering the expansion of expressions like (A – B)^2, you’ll enhance your algebraic skills and be better equipped to tackle more advanced mathematical concepts and problem-solving challenges.