The problem asks us to find the domain of the given functions. We need to consider cases where we have square roots (the expression inside must be non-negative) and fractions (the denominator cannot be zero).

AlgebraDomainFunctionsSquare RootsFractionsInequalitiesQuadratic Equations
2025/3/15

1. Problem Description

The problem asks us to find the domain of the given functions. We need to consider cases where we have square roots (the expression inside must be non-negative) and fractions (the denominator cannot be zero).

2. Solution Steps

1. $f(x) = \frac{\sqrt{2x-10}}{x-7}$

We need 2x1002x-10 \ge 0 and x70x-7 \ne 0.
2x10    x52x \ge 10 \implies x \ge 5.
x7x \ne 7.
So, the domain is [5,7)(7,)[5, 7) \cup (7, \infty).

2. $f(x) = \frac{2}{x^2 + 3x}$

We need x2+3x0x^2 + 3x \ne 0.
x(x+3)0    x0x(x+3) \ne 0 \implies x \ne 0 and x3x \ne -3.
So, the domain is (,3)(3,0)(0,)(-\infty, -3) \cup (-3, 0) \cup (0, \infty).

3. $f(x) = \frac{4x-1}{\sqrt{5-2x}}$

We need 52x>05-2x > 0.
5>2x    x<525 > 2x \implies x < \frac{5}{2}.
So, the domain is (,52)(-\infty, \frac{5}{2}).

4. $f(x) = \sqrt{\frac{3x-1}{x+4}}$

We need 3x1x+40\frac{3x-1}{x+4} \ge 0.
Case 1: 3x103x-1 \ge 0 and x+4>0x+4 > 0.
x13x \ge \frac{1}{3} and x>4x > -4. Thus x13x \ge \frac{1}{3}.
Case 2: 3x103x-1 \le 0 and x+4<0x+4 < 0.
x13x \le \frac{1}{3} and x<4x < -4. Thus x<4x < -4.
So, the domain is (,4)[13,)(-\infty, -4) \cup [\frac{1}{3}, \infty).

5. $f(x) = \frac{\sqrt{3x-1}}{\sqrt{x+4}}$

We need 3x103x-1 \ge 0 and x+4>0x+4 > 0.
3x1    x133x \ge 1 \implies x \ge \frac{1}{3}.
x>4x > -4.
So, the domain is [13,)[\frac{1}{3}, \infty).

6. $f(x) = \sqrt{x^2 - 11x + 18}$

We need x211x+180x^2 - 11x + 18 \ge 0.
x211x+18=(x2)(x9)x^2 - 11x + 18 = (x-2)(x-9).
So we need (x2)(x9)0(x-2)(x-9) \ge 0.
Case 1: x20x-2 \ge 0 and x90x-9 \ge 0.
x2x \ge 2 and x9x \ge 9. Thus x9x \ge 9.
Case 2: x20x-2 \le 0 and x90x-9 \le 0.
x2x \le 2 and x9x \le 9. Thus x2x \le 2.
So, the domain is (,2][9,)(-\infty, 2] \cup [9, \infty).

7. $f(x) = \frac{2+x}{\sqrt{4x-1}}$

We need 4x1>04x-1 > 0.
4x>1    x>144x > 1 \implies x > \frac{1}{4}.
So, the domain is (14,)(\frac{1}{4}, \infty).

8. $f(x) = \sqrt{\frac{x^2 - 25}{8-x}}$

We need x2258x0\frac{x^2 - 25}{8-x} \ge 0.
(x5)(x+5)8x0\frac{(x-5)(x+5)}{8-x} \ge 0.
Case 1: (x5)(x+5)0(x-5)(x+5) \ge 0 and 8x>08-x > 0.
x5x \le -5 or x5x \ge 5, and x<8x < 8. Thus x(,5][5,8)x \in (-\infty, -5] \cup [5, 8).
Case 2: (x5)(x+5)0(x-5)(x+5) \le 0 and 8x<08-x < 0.
5x5-5 \le x \le 5 and x>8x > 8. No solution.
So, the domain is (,5][5,8)(-\infty, -5] \cup [5, 8).

9. $f(x) = \frac{1}{x^2 + 2x + 5}$

We need x2+2x+50x^2 + 2x + 5 \ne 0.
x2+2x+5=(x+1)2+4x^2 + 2x + 5 = (x+1)^2 + 4. Since (x+1)20(x+1)^2 \ge 0, (x+1)2+44>0(x+1)^2 + 4 \ge 4 > 0.
So the denominator is always non-zero.
So, the domain is (,)(-\infty, \infty).
1

0. $f(x) = \frac{\sqrt{x+3}}{\sqrt{x^2-4}}$

We need x+30x+3 \ge 0 and x24>0x^2-4 > 0.
x3x \ge -3 and (x2)(x+2)>0(x-2)(x+2) > 0.
x3x \ge -3 and (x>2x > 2 or x<2x < -2).
Combining these, we have [3,2)(2,)[-3, -2) \cup (2, \infty).

3. Final Answer

1. $[5, 7) \cup (7, \infty)$

2. $(-\infty, -3) \cup (-3, 0) \cup (0, \infty)$

3. $(-\infty, \frac{5}{2})$

4. $(-\infty, -4) \cup [\frac{1}{3}, \infty)$

5. $[\frac{1}{3}, \infty)$

6. $(-\infty, 2] \cup [9, \infty)$

7. $(\frac{1}{4}, \infty)$

8. $(-\infty, -5] \cup [5, 8)$

9. $(-\infty, \infty)$

1

0. $[-3, -2) \cup (2, \infty)$

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