Предмет: Алгебра, автор: polomkamaksik

7,8 завдання! БУДЬ ЛАСКА ЧИМ ПОБИСТРІШЕ ТРЕБА РОЗВ'ЯЗОК(БЕЗ ДИСКРИМІНАНТА,7 КЛАС ВИРАЗИ)

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Автор ответа: heyy60

1

Ответ:

$7. \: (2x + 3)^{2} - (x - 1)^{2} = ((2x + 3) - (x - 1)) \times \\ \times (2x + 3 + x - 1) = (x + 4)(3x + 2) \\ \\ 8)9x ^{2} - 4 = 0 \\ (3x - 2)(3x + 2) = 0 \\ \\ 3x - 2 = 0 \\ 3x = 2 \\ x_{1} = \frac{2}{3} \\ \\ 3x + 2 = 0 \\ 3x = - 2 \\ x_{2} = - \frac{2}{3}$

polomkamaksik: спасибо

polomkamaksik: якщо не важко то можеш ще виконати от це завдання: Доведіть, що вираз x2-4x+5 набуває додатних значень при всіх значеннях x. Якого найменшого значення набуває вираз і при якому значенні х?

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