Question: b) $\frac{5x^2 + 15x}{2x+6} : \left(1 + \frac{5}{2x}\right)$
please factorize the given fraction
1. **State the problem:**
Factorize and simplify the expression $$\frac{5x^2 + 15x}{2x+6} : \left(1 + \frac{5}{2x}\right)$$.
2. **Rewrite the division as multiplication by the reciprocal:**
$$\frac{5x^2 + 15x}{2x+6} \times \frac{1}{1 + \frac{5}{2x}}$$
3. **Factor the numerator and denominator where possible:**
- Numerator: $$5x^2 + 15x = 5x(x + 3)$$
- Denominator: $$2x + 6 = 2(x + 3)$$
4. **Simplify the first fraction:**
$$\frac{5x(x + 3)}{2(x + 3)}$$
Cancel the common factor $\cancel{(x + 3)}$:
$$\frac{5x\cancel{(x + 3)}}{2\cancel{(x + 3)}} = \frac{5x}{2}$$
5. **Simplify the second term inside the reciprocal:**
$$1 + \frac{5}{2x} = \frac{2x}{2x} + \frac{5}{2x} = \frac{2x + 5}{2x}$$
6. **Take the reciprocal:**
$$\frac{1}{1 + \frac{5}{2x}} = \frac{1}{\frac{2x + 5}{2x}} = \frac{2x}{2x + 5}$$
7. **Multiply the simplified first fraction by the reciprocal:**
$$\frac{5x}{2} \times \frac{2x}{2x + 5} = \frac{5x \times 2x}{2 \times (2x + 5)} = \frac{10x^2}{2(2x + 5)}$$
8. **Simplify the fraction by canceling common factors:**
$$\frac{\cancel{10}x^2}{\cancel{2}(2x + 5)} = \frac{5x^2}{2x + 5}$$
**Final answer:**
$$\boxed{\frac{5x^2}{2x + 5}}$$