1. **State the problem:**
We have the function $f(x) = x^2 - x - 2$ and need to:
(i) Simplify $\frac{f(x)}{f(x+3)}$ to $\frac{x-2}{x+4}$ when $f(x+3) \neq 0$.
(ii) Find the range of $x$ such that $\frac{f(x)}{f(x+3)} < 2$ with $x \neq -4$.
2. **Recall the formula and factorization:**
The quadratic $f(x) = x^2 - x - 2$ factors as:
$$f(x) = (x - 2)(x + 1)$$
Similarly, for $f(x+3)$:
$$f(x+3) = (x+3)^2 - (x+3) - 2$$
3. **Simplify $f(x+3)$:**
$$f(x+3) = (x+3)^2 - (x+3) - 2 = (x^2 + 6x + 9) - x - 3 - 2 = x^2 + 5x + 4$$
Factor $f(x+3)$:
$$x^2 + 5x + 4 = (x + 4)(x + 1)$$
4. **Write the fraction and simplify:**
$$\frac{f(x)}{f(x+3)} = \frac{(x - 2)(x + 1)}{(x + 4)(x + 1)}$$
Cancel the common factor $(x + 1)$ (not zero to avoid division by zero):
$$\frac{(x - 2)\cancel{(x + 1)}}{(x + 4)\cancel{(x + 1)}}$$
So,
$$\frac{f(x)}{f(x+3)} = \frac{x - 2}{x + 4}$$
5. **Condition for simplification:**
$f(x+3) \neq 0$ means $(x + 4)(x + 1) \neq 0$, so $x \neq -4$ and $x \neq -1$.
6. **Solve inequality:**
$$\frac{f(x)}{f(x+3)} < 2 \implies \frac{x - 2}{x + 4} < 2$$
Rewrite:
$$\frac{x - 2}{x + 4} - 2 < 0$$
$$\frac{x - 2 - 2(x + 4)}{x + 4} < 0$$
Simplify numerator:
$$x - 2 - 2x - 8 = -x - 10$$
So inequality is:
$$\frac{-x - 10}{x + 4} < 0$$
Or equivalently:
$$\frac{-(x + 10)}{x + 4} < 0$$
7. **Analyze sign:**
The fraction is negative when numerator and denominator have opposite signs.
- Numerator $-(x + 10)$ is positive when $x + 10 < 0 \Rightarrow x < -10$.
- Numerator is negative when $x > -10$.
- Denominator $x + 4$ is positive when $x > -4$.
- Denominator is negative when $x < -4$.
8. **Check intervals:**
- For $x < -10$: numerator positive, denominator negative (since $x < -4$), fraction negative $\Rightarrow$ inequality holds.
- For $-10 < x < -4$: numerator negative, denominator negative, fraction positive $\Rightarrow$ inequality does not hold.
- For $x > -4$: numerator negative, denominator positive, fraction negative $\Rightarrow$ inequality holds.
9. **Exclude points where denominator zero:**
$x \neq -4$ (given), also $x \neq -1$ from simplification step.
10. **Final solution:**
$$x < -10 \quad \text{or} \quad x > -4, \quad x \neq -1$$
**Answer:**
(i) $\frac{f(x)}{f(x+3)} = \frac{x - 2}{x + 4}$ for $x \neq -4, -1$.
(ii) $\frac{f(x)}{f(x+3)} < 2$ for $x < -10$ or $x > -4$ with $x \neq -1$.
Function Ratio B59017
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