1. **State the problem:** We have a rectangle with original length $L$ and width $W$. When the length is increased by 2 cm, the area becomes 36 cm². When the width is increased by 3 cm, the area becomes 49 cm². We need to find the original width $W$.
2. **Write the equations from the problem:**
- Increasing length by 2 cm: $$(L + 2) \times W = 36$$
- Increasing width by 3 cm: $$L \times (W + 3) = 49$$
3. **Express $L$ from the first equation:**
$$L + 2 = \frac{36}{W} \implies L = \frac{36}{W} - 2$$
4. **Substitute $L$ into the second equation:**
$$\left(\frac{36}{W} - 2\right) \times (W + 3) = 49$$
5. **Expand and simplify:**
$$\left(\frac{36}{W} - 2\right)(W + 3) = 49$$
$$\frac{36}{W} \times (W + 3) - 2(W + 3) = 49$$
$$36 \times \frac{W + 3}{W} - 2W - 6 = 49$$
6. **Rewrite the fraction:**
$$36 \times \left(1 + \frac{3}{W}\right) - 2W - 6 = 49$$
$$36 + \frac{108}{W} - 2W - 6 = 49$$
7. **Combine like terms:**
$$30 + \frac{108}{W} - 2W = 49$$
8. **Isolate terms:**
$$\frac{108}{W} - 2W = 19$$
9. **Multiply both sides by $W$ to clear denominator:**
$$\cancel{W} \times \frac{108}{\cancel{W}} - 2W \times W = 19W$$
$$108 - 2W^2 = 19W$$
10. **Rearrange to standard quadratic form:**
$$-2W^2 - 19W + 108 = 0$$
Multiply both sides by $-1$ to simplify:
$$2W^2 + 19W - 108 = 0$$
11. **Solve quadratic equation:**
Use quadratic formula:
$$W = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=2$, $b=19$, $c=-108$.
Calculate discriminant:
$$\Delta = 19^2 - 4 \times 2 \times (-108) = 361 + 864 = 1225$$
Square root:
$$\sqrt{1225} = 35$$
Calculate roots:
$$W = \frac{-19 \pm 35}{2 \times 2} = \frac{-19 \pm 35}{4}$$
Two solutions:
- $$W = \frac{-19 + 35}{4} = \frac{16}{4} = 4$$
- $$W = \frac{-19 - 35}{4} = \frac{-54}{4} = -13.5$$ (not possible since width must be positive)
12. **Final answer:** The original width is $\boxed{4}$ cm.
**Answer choice:** 4 cm
Rectangle Width 4F3Bb3
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