Complex Expression
1. **State the problem:** We need to simplify the expression $$(1 + 2i^2)(1 + 2i^5 + 5i^6)$$ and write it in the form $x + yi$ where $x$ and $y$ are real numbers.
2. **Recall powers of $i$:** Remember that $i$ is the imaginary unit where $i^2 = -1$.
Powers of $i$ cycle every 4 steps:
$$i^1 = i, \quad i^2 = -1, \quad i^3 = -i, \quad i^4 = 1,$$
and this pattern repeats.
3. **Simplify each power:**
- $i^2 = -1$
- $i^5 = i^{4+1} = i^4 \cdot i = 1 \cdot i = i$
- $i^6 = i^{4+2} = i^4 \cdot i^2 = 1 \cdot (-1) = -1$
4. **Substitute back into the expression:**
$$(1 + 2(-1))(1 + 2i + 5(-1)) = (1 - 2)(1 + 2i - 5) = (-1)(-4 + 2i)$$
5. **Multiply:**
$$-1 \times (-4) = 4$$
$$-1 \times 2i = -2i$$
6. **Write final expression:**
$$4 - 2i$$
**Answer:** The expression in the form $x + yi$ is $$4 - 2i$$.