To simplify the expressions in the image you provided, let's work through the exercises step by step.

### Bài 1: Rút gọn biểu thức

**Phần a:**
\[ A = \sqrt{9a} - \sqrt{16a} + \sqrt{49a} \]
\[ = 3\sqrt{a} - 4\sqrt{a} + 7\sqrt{a} \]
\[ = (3 - 4 + 7)\sqrt{a} = 6\sqrt{a} \]

**Phần b:**
\[ B = 5\sqrt{1+x} + 8\sqrt{4+x} + 4 - \sqrt{9+9+x} \]
Due to its complexity, this expression typically requires specific values for consolidation or numerical simplification based on additional context.

### Bài 2: Dura thừa số vào trong dấu căn

**Phần a:**
\[ \sqrt{3^2} = 3 \]

**Phần b:**
\[ -\sqrt{3^2} = -3 \]

**Phần c:**
\[ \sqrt{-\frac{23}{x}}, \quad x < 0 \]
(Since the expression under the square root is negative, it cannot be simplified further in real numbers and implies an imaginary number context).

**Phần d:**
\[ 2\sqrt{\frac{y}{2x}}, \quad x > 0, y > 0 \]
(Simplifying yields \( \sqrt{\frac{2y}{x}} \) or left in fractional form).

### Bài 3: Giải phương trình

Please provide more information on how to proceed since the method varies based on each equation's structure.

### Bài 4: Giải bất phương trình

Similar to Bài 3, please specify the task requirements for clarity.

### Bài 5: Trực căn có dạng:

**Phần a:**
\[ \frac{a + b/\sqrt{a}}{2a^2} \quad \text{(simplifies based on the values of }a\text{ and }b\text{)} \]

If you have specific parts of the homework you'd like me to focus on or any questions pertaining to those sections, please indicate!