Решим уравнения:
a) \[\frac{15}{x-2} = \frac{14}{x} + 1\]
Приведем к общему знаменателю \(x(x-2)\):
\[\frac{15x}{x(x-2)} = \frac{14(x-2)}{x(x-2)} + \frac{x(x-2)}{x(x-2)}\]
\[15x = 14x - 28 + x^2 - 2x\]
\[x^2 + 14x - 2x - 15x - 28 = 0\]
\[x^2 - 3x - 28 = 0\]
\(
D = (-3)^2 - 4 \cdot 1 \cdot (-28) = 9 + 112 = 121\)
\(
x_1 = \frac{3 + 11}{2} = 7\)
\(
x_2 = \frac{3 - 11}{2} = -4\)
б) \[
\frac{2}{x-3} + \frac{14}{x} = 3\]
Приведем к общему знаменателю \(x(x-3)\):
\[\frac{2x}{x(x-3)} + \frac{14(x-3)}{x(x-3)} = \frac{3x(x-3)}{x(x-3)}\]
\(
2x + 14x - 42 = 3x^2 - 9x
\)
\(
3x^2 - 9x - 16x + 42 = 0
\)
\(
3x^2 - 25x + 42 = 0
\)
\(
D = (-25)^2 - 4 \cdot 3 \cdot 42 = 625 - 504 = 121
\)
\(
x_1 = \frac{25 + 11}{6} = 6\)
\(
x_2 = \frac{25 - 11}{6} = \frac{7}{3}\)
в) \[
\frac{1}{x-3} + \frac{1}{x} = -\frac{5}{4}\]
Приведем к общему знаменателю \(4x(x-3)\):
\[\frac{4x}{4x(x-3)} + \frac{4(x-3)}{4x(x-3)} = -\frac{5x(x-3)}{4x(x-3)}\]
\(
4x + 4x - 12 = -5x^2 + 15x
\)
\(
5x^2 + 8x - 15x - 12 = 0
\)
\(
5x^2 - 7x - 12 = 0
\)
\(
D = (-7)^2 - 4 \cdot 5 \cdot (-12) = 49 + 240 = 289
\)
\(
x_1 = \frac{7 + 17}{10} = \frac{12}{5}
\)
\(
x_2 = \frac{7 - 17}{10} = -1
\)
г) \[
\frac{1}{x} + \frac{1}{x+3} = -\frac{3}{20}\]
Приведем к общему знаменателю \(20x(x+3)\):
\[\frac{20(x+3)}{20x(x+3)} + \frac{20x}{20x(x+3)} = -\frac{3x(x+3)}{20x(x+3)}\]
\[
20x + 60 + 20x = -3x^2 - 9x
\]
\[
3x^2 + 40x + 9x + 60 = 0
\]
\[
3x^2 + 49x + 60 = 0
\]
\(
D = 49^2 - 4 \cdot 3 \cdot 60 = 2401 - 720 = 1681\)
\(
x_1 = \frac{-49 + 41}{6} = -\frac{4}{3}
\)
\(
x_2 = \frac{-49 - 41}{6} = -15
\)
д) \[
\frac{40}{x-20} - \frac{40}{x} = 1\]
Приведем к общему знаменателю \(x(x-20)\):
\[\frac{40x}{x(x-20)} - \frac{40(x-20)}{x(x-20)} = \frac{x(x-20)}{x(x-20)}\]
\[
40x - 40x + 800 = x^2 - 20x
\]
\[
x^2 - 20x - 800 = 0
\]
\(
D = (-20)^2 - 4 \cdot 1 \cdot (-800) = 400 + 3200 = 3600
\)
\(
x_1 = \frac{20 + 60}{2} = 40
\)
\(
x_2 = \frac{20 - 60}{2} = -20
\)
e) \[
\frac{120}{x} - \frac{120}{x+4} = 1\]
Приведем к общему знаменателю \(x(x+4)\):
\[\frac{120(x+4)}{x(x+4)} - \frac{120x}{x(x+4)} = \frac{x(x+4)}{x(x+4)}\]
\(
120x + 480 - 120x = x^2 + 4x
\)
\(
x^2 + 4x - 480 = 0
\)
\(
D = 4^2 - 4 \cdot 1 \cdot (-480) = 16 + 1920 = 1936
\)
\(
x_1 = \frac{-4 + 44}{2} = 20
\)
\(
x_2 = \frac{-4 - 44}{2} = -24
\)
ж) \[
\frac{180}{x} - 1 = \frac{180}{x+6}\]
Приведем к общему знаменателю \(x(x+6)\):
\[\frac{180(x+6)}{x(x+6)} - \frac{x(x+6)}{x(x+6)} = \frac{180x}{x(x+6)}\]
\(
180x + 1080 - x^2 - 6x = 180x
\)
\(
x^2 + 6x - 1080 = 0
\)
\(
D = 6^2 - 4 \cdot 1 \cdot (-1080) = 36 + 4320 = 4356
\)
\(
x_1 = \frac{-6 + 66}{2} = 30
\)
\(
x_2 = \frac{-6 - 66}{2} = -36
\)
3) \[
\frac{2}{x-1} + \frac{4}{x} = 4\]
Приведем к общему знаменателю \(x(x-1)\):
\[\frac{2x}{x(x-1)} + \frac{4(x-1)}{x(x-1)} = \frac{4x(x-1)}{x(x-1)}\]
\(
2x + 4x - 4 = 4x^2 - 4x
\)
\(
4x^2 - 4x - 6x + 4 = 0
\)
\(
4x^2 - 10x + 4 = 0
\)
\(
2x^2 - 5x + 2 = 0
\)
\(
D = (-5)^2 - 4 \cdot 2 \cdot 2 = 25 - 16 = 9
\)
\(
x_1 = \frac{5 + 3}{4} = 2
\)
\(
x_2 = \frac{5 - 3}{4} = \frac{1}{2}
\)
Ответ: a) x = 7, x = -4; б) x = 6, x = 7/3; в) x = 12/5, x = -1; г) x = -4/3, x = -15; д) x = 40, x = -20; e) x = 20, x = -24; ж) x = 30, x = -36; 3) x = 2, x = 1/2
Отлично! Ты хорошо справился с решением этих уравнений. Продолжай в том же духе и у тебя все получится!