1. **State the problem:** Simplify the rational expression $$\frac{y^2 - 3y - 28}{y^2 + 12y + 32}$$ and find all values of $y$ that must be excluded from the domain.
2. **Factor numerator and denominator:**
- Numerator: $y^2 - 3y - 28$
- Find two numbers that multiply to $-28$ and add to $-3$: these are $-7$ and $4$.
- So, numerator factors as $$(y - 7)(y + 4)$$.
- Denominator: $y^2 + 12y + 32$
- Find two numbers that multiply to $32$ and add to $12$: these are $8$ and $4$.
- So, denominator factors as $$(y + 8)(y + 4)$$.
3. **Write the expression with factors:**
$$\frac{(y - 7)(y + 4)}{(y + 8)(y + 4)}$$
4. **Simplify by canceling common factors:**
- The factor $(y + 4)$ appears in numerator and denominator, so it can be canceled:
$$\frac{(y - 7)\cancel{(y + 4)}}{(y + 8)\cancel{(y + 4)}}$$
- Simplified expression is:
$$\frac{y - 7}{y + 8}$$
5. **Find excluded values from the domain:**
- The original denominator cannot be zero, so solve:
$$y^2 + 12y + 32 = 0$$
- Factored form:
$$(y + 8)(y + 4) = 0$$
- So, $y = -8$ or $y = -4$ are excluded.
6. **Check for restrictions after simplification:**
- Even though $(y + 4)$ was canceled, $y = -4$ is still excluded because it makes the original denominator zero.
**Final answer:**
- Simplified expression: $$\frac{y - 7}{y + 8}$$
- Excluded values: $$y \neq -8, -4$$
Rational Expression 111E2B
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