Expanding (x+2y)²
The expression (x+2y)² represents the square of the binomial (x+2y). To expand this expression, we can use the FOIL method or the square of a binomial formula.
Using the FOIL Method
FOIL stands for First, Outer, Inner, Last. It's a way to remember how to multiply two binomials.
- First: Multiply the first terms of each binomial: x * x = x²
- Outer: Multiply the outer terms of the binomials: x * 2y = 2xy
- Inner: Multiply the inner terms of the binomials: 2y * x = 2xy
- Last: Multiply the last terms of each binomial: 2y * 2y = 4y²
Now, add all the terms together: x² + 2xy + 2xy + 4y²
Combining like terms, we get: x² + 4xy + 4y²
Using the Square of a Binomial Formula
The square of a binomial formula states: (a + b)² = a² + 2ab + b²
In our case, a = x and b = 2y. Applying the formula:
(x + 2y)² = x² + 2(x)(2y) + (2y)²
Simplifying, we get: x² + 4xy + 4y²
Conclusion
Both methods, the FOIL method and the square of a binomial formula, lead to the same answer. The expanded form of (x+2y)² is x² + 4xy + 4y². This expression represents a trinomial with three terms: a squared term (x²), a linear term (4xy), and a squared term (4y²).