Номер 260, страница 81 - гдз по алгебре 9 класс учебник Солтан, Солтан

Алгебра, 9 класс Учебник, авторы: Солтан Генадий Николаевич, Солтан Алла Евгеньевна, Жумадилова Аманбала Жумадиловна, издательство Кокшетау, Алматы, 2019

Авторы: Солтан Г. Н., Солтан А. Е., Жумадилова А. Ж.

Тип: Учебник

Издательство: Кокшетау

Год издания: 2019 - 2026

ISBN: 978-601-317-424-2

Рекомендовано Министерством образования и науки Республики Казахстан

II. Элементы комбинаторики. 10. Сочетания без повторений - номер 260, страница 81.

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            "text" => "<p><strong>а)</strong> Чтобы найти число хорд окружности с концами в данных 12 точках, необходимо посчитать, сколькими способами можно выбрать 2 точки из 12. Каждая пара точек однозначно определяет одну хорду. Порядок выбора точек не важен (хорда между точками A и B — это та же самая хорда, что и между B и A), поэтому мы используем формулу для числа сочетаний.</p><p>Формула числа сочетаний из $n$ элементов по $k$: $C_n^k = \frac{n!}{k!(n-k)!}$.</p><p>В данном случае общее число точек $n = 12$, а для построения хорды нам нужно выбрать $k = 2$ точки.</p><p>Подставляем значения в формулу: $C_{12}^2 = \frac{12!}{2!(12-2)!} = \frac{12!}{2! \cdot 10!} = \frac{11 \cdot 12}{2 \cdot 1} = 66$.</p><p>Таким образом, можно построить 66 различных хорд.</p><p><strong>Ответ:</strong> 66</p><p><strong>б)</strong> Чтобы найти число треугольников с вершинами в этих точках, нужно определить, сколькими способами можно выбрать 3 точки из 12. Так как все 12 точек лежат на окружности, любые три из них не будут лежать на одной прямой, а значит, всегда будут образовывать треугольник. Порядок выбора вершин треугольника также не имеет значения.</p><p>Мы снова используем формулу для числа сочетаний. Здесь общее число точек $n = 12$, а для построения треугольника нужно выбрать $k = 3$ точки (вершины).</p><p>Подставляем значения в формулу: $C_{12}^3 = \frac{12!}{3!(12-3)!} = \frac{12!}{3! \cdot 9!} = \frac{10 \cdot 11 \cdot 12}{3 \cdot 2 \cdot 1} = \frac{1320}{6} = 220$.</p><p>Таким образом, можно построить 220 различных треугольников.</p><p><strong>Ответ:</strong> 220</p>"
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            "text" => "<p><strong>а)</strong> Чтобы найти число хорд окружности с концами в данных 12 точках, необходимо посчитать, сколькими способами можно выбрать 2 точки из 12. Каждая пара точек однозначно определяет одну хорду. Порядок выбора точек не важен (хорда между точками A и B — это та же самая хорда, что и между B и A), поэтому мы используем формулу для числа сочетаний.</p><p>Формула числа сочетаний из $n$ элементов по $k$: $C_n^k = \frac{n!}{k!(n-k)!}$.</p><p>В данном случае общее число точек $n = 12$, а для построения хорды нам нужно выбрать $k = 2$ точки.</p><p>Подставляем значения в формулу: $C_{12}^2 = \frac{12!}{2!(12-2)!} = \frac{12!}{2! \cdot 10!} = \frac{11 \cdot 12}{2 \cdot 1} = 66$.</p><p>Таким образом, можно построить 66 различных хорд.</p><p><strong>Ответ:</strong> 66</p><p><strong>б)</strong> Чтобы найти число треугольников с вершинами в этих точках, нужно определить, сколькими способами можно выбрать 3 точки из 12. Так как все 12 точек лежат на окружности, любые три из них не будут лежать на одной прямой, а значит, всегда будут образовывать треугольник. Порядок выбора вершин треугольника также не имеет значения.</p><p>Мы снова используем формулу для числа сочетаний. Здесь общее число точек $n = 12$, а для построения треугольника нужно выбрать $k = 3$ точки (вершины).</p><p>Подставляем значения в формулу: $C_{12}^3 = \frac{12!}{3!(12-3)!} = \frac{12!}{3! \cdot 9!} = \frac{10 \cdot 11 \cdot 12}{3 \cdot 2 \cdot 1} = \frac{1320}{6} = 220$.</p><p>Таким образом, можно построить 220 различных треугольников.</p><p><strong>Ответ:</strong> 220</p>"
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    "page" => Illuminate\Database\Eloquent\Collection {#1472
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        0 => App\Models\BookPage {#1032
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            }
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                0 => App\Models\Book {#1193
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1194 …2}
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                    "field_series" => Illuminate\Database\Eloquent\Collection {#1212 …2}
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                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1214 …2}
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                    "field_cover" => array:1 [ …1]
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                    "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik"
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                  ]
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                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1194 …2}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1197 …2}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1199 …2}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1201 …2}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1205 …2}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1206 …2}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1208 …2}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1210 …2}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1212 …2}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1213 …2}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1214 …2}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1215 …2}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1216 …2}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1217 …2}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => null
                    "field_publication_year" => "2019"
                    "field_publication_year_until" => null
                    "field_part" => ""
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                    "field_second_foreign_language" => null
                     …23
                  ]
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                }
              ]
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            "edition_groups" => Illuminate\Database\Eloquent\Collection {#1222
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            }
            "content" => Illuminate\Database\Eloquent\Collection {#1223
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                0 => App\Models\Element {#1224
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                  #attributes: array:6 [ …6]
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                  #guarded: array:1 [ …1]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "next" => array:2 [
              "refs" => "1097824"
              "type" => "book_page"
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            "tasks" => Illuminate\Database\Eloquent\Collection {#1232
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                  #connection: "mysql"
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                  #keyType: "int"
                  +incrementing: true
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                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
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                  #touches: []
                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                1 => App\Models\Task {#1327
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                2 => App\Models\Task {#1340
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
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                  #attributeCastCache: []
                  #dateFormat: null
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                  #touches: []
                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                3 => App\Models\Task {#1353
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
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                  #attributeCastCache: []
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                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                4 => App\Models\Task {#1366
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
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                  #attributeCastCache: []
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                  +timestamps: true
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                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [ …1]
                }
                5 => App\Models\Task {#1379
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [ …24]
                  #original: array:24 [ …24]
                  #changes: []
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№260 (с. 81)
Условие. №260 (с. 81)
скриншот условия
Алгебра, 9 класс Учебник, авторы: Солтан Генадий Николаевич, Солтан Алла Евгеньевна, Жумадилова Аманбала Жумадиловна, издательство Кокшетау, Алматы, 2019, страница 81, номер 260, Условие

260. На окружности последовательно отмечены 12 точек. Найдите число:

а) хорд окружности с концами в этих точках;

б) треугольников с вершинами в этих точках.

Решение. №260 (с. 81)
Алгебра, 9 класс Учебник, авторы: Солтан Генадий Николаевич, Солтан Алла Евгеньевна, Жумадилова Аманбала Жумадиловна, издательство Кокшетау, Алматы, 2019, страница 81, номер 260, Решение
Решение 2 (rus). №260 (с. 81)

а) Чтобы найти число хорд окружности с концами в данных 12 точках, необходимо посчитать, сколькими способами можно выбрать 2 точки из 12. Каждая пара точек однозначно определяет одну хорду. Порядок выбора точек не важен (хорда между точками A и B — это та же самая хорда, что и между B и A), поэтому мы используем формулу для числа сочетаний.

Формула числа сочетаний из $n$ элементов по $k$: $C_n^k = \frac{n!}{k!(n-k)!}$.

В данном случае общее число точек $n = 12$, а для построения хорды нам нужно выбрать $k = 2$ точки.

Подставляем значения в формулу: $C_{12}^2 = \frac{12!}{2!(12-2)!} = \frac{12!}{2! \cdot 10!} = \frac{11 \cdot 12}{2 \cdot 1} = 66$.

Таким образом, можно построить 66 различных хорд.

Ответ: 66

б) Чтобы найти число треугольников с вершинами в этих точках, нужно определить, сколькими способами можно выбрать 3 точки из 12. Так как все 12 точек лежат на окружности, любые три из них не будут лежать на одной прямой, а значит, всегда будут образовывать треугольник. Порядок выбора вершин треугольника также не имеет значения.

Мы снова используем формулу для числа сочетаний. Здесь общее число точек $n = 12$, а для построения треугольника нужно выбрать $k = 3$ точки (вершины).

Подставляем значения в формулу: $C_{12}^3 = \frac{12!}{3!(12-3)!} = \frac{12!}{3! \cdot 9!} = \frac{10 \cdot 11 \cdot 12}{3 \cdot 2 \cdot 1} = \frac{1320}{6} = 220$.

Таким образом, можно построить 220 различных треугольников.

Ответ: 220

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