1. **State the problem:** Solve the inequality $$\frac{10 - 4x}{x^2 - 7x + 10} > 3$$.
2. **Rewrite the inequality:** Move all terms to one side to compare to zero:
$$\frac{10 - 4x}{x^2 - 7x + 10} - 3 > 0$$
3. **Find a common denominator and combine:**
$$\frac{10 - 4x - 3(x^2 - 7x + 10)}{x^2 - 7x + 10} > 0$$
4. **Expand the numerator:**
$$10 - 4x - 3x^2 + 21x - 30 = -3x^2 + 17x - 20$$
5. **Rewrite the inequality:**
$$\frac{-3x^2 + 17x - 20}{x^2 - 7x + 10} > 0$$
6. **Factor numerator and denominator:**
- Denominator: $$x^2 - 7x + 10 = (x - 5)(x - 2)$$
- Numerator: Find factors of $$-3x^2 + 17x - 20$$
Try factoring numerator:
$$-3x^2 + 17x - 20 = -(3x^2 - 17x + 20)$$
Find factors of $$3x^2 - 17x + 20$$:
Try $$(3x - 5)(x - 4) = 3x^2 - 12x - 5x + 20 = 3x^2 - 17x + 20$$
So numerator:
$$-(3x - 5)(x - 4)$$
7. **Rewrite inequality with factors:**
$$\frac{-(3x - 5)(x - 4)}{(x - 5)(x - 2)} > 0$$
8. **Simplify by factoring out the negative sign:**
$$\frac{-(3x - 5)(x - 4)}{(x - 5)(x - 2)} = - \frac{(3x - 5)(x - 4)}{(x - 5)(x - 2)}$$
So inequality is:
$$- \frac{(3x - 5)(x - 4)}{(x - 5)(x - 2)} > 0$$
9. **Multiply both sides by -1 (flip inequality):**
$$\frac{(3x - 5)(x - 4)}{(x - 5)(x - 2)} < 0$$
10. **Identify critical points:**
- Numerator zeros: $$3x - 5 = 0 \Rightarrow x = \frac{5}{3}$$, $$x - 4 = 0 \Rightarrow x = 4$$
- Denominator zeros (excluded from domain): $$x = 2, 5$$
11. **Determine sign intervals:**
Intervals to test: $$(-\infty, 2), (2, \frac{5}{3}), (\frac{5}{3}, 4), (4, 5), (5, \infty)$$
Note $$\frac{5}{3} \approx 1.666$$ so order is $$(-\infty, \frac{5}{3}), (\frac{5}{3}, 2), (2, 4), (4, 5), (5, \infty)$$
12. **Test each interval:**
- For $$x < \frac{5}{3}$$ (e.g., 1): numerator factors: $(3(1)-5) = -2$ (negative), $(1-4) = -3$ (negative), numerator positive (negative*negative).
Denominator: $(1-5) = -4$ (negative), $(1-2) = -1$ (negative), denominator positive.
Fraction positive, but inequality requires fraction < 0, so no.
- For $$\frac{5}{3} < x < 2$$ (e.g., 1.8): numerator: $(3(1.8)-5) = 0.4$ (positive), $(1.8-4) = -2.2$ (negative), numerator negative.
Denominator: $(1.8-5) = -3.2$ (negative), $(1.8-2) = -0.2$ (negative), denominator positive.
Fraction negative < 0, satisfies inequality.
- For $$2 < x < 4$$ (e.g., 3): numerator: $(3(3)-5) = 4$ (positive), $(3-4) = -1$ (negative), numerator negative.
Denominator: $(3-5) = -2$ (negative), $(3-2) = 1$ (positive), denominator negative.
Fraction negative/negative = positive > 0, no.
- For $$4 < x < 5$$ (e.g., 4.5): numerator: $(3(4.5)-5) = 8.5$ (positive), $(4.5-4) = 0.5$ (positive), numerator positive.
Denominator: $(4.5-5) = -0.5$ (negative), $(4.5-2) = 2.5$ (positive), denominator negative.
Fraction positive/negative = negative < 0, satisfies inequality.
- For $$x > 5$$ (e.g., 6): numerator: $(3(6)-5) = 13$ (positive), $(6-4) = 2$ (positive), numerator positive.
Denominator: $(6-5) = 1$ (positive), $(6-2) = 4$ (positive), denominator positive.
Fraction positive > 0, no.
13. **Domain restrictions:** Exclude $$x=2$$ and $$x=5$$ because denominator zero.
14. **Final solution set:**
$$\left(\frac{5}{3}, 2\right) \cup (4, 5)$$
**Answer:** The solution set is $$\boxed{\left(\frac{5}{3}, 2\right) \cup (4, 5)}$$.
Rational Inequality 25539B
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