Предмет: Алгебра, автор: Polli2100

Решите уравнение: 31-3x-x²=20x+7(x-2)²

Ответы

Автор ответа: Juliaa21

31-3x-x²=20x+7(x²-4x+4)
31-3x-x²=20x+7x²-28x+28
-x²-7x²-3x-20x+28x+31-28=0
-8x²+5x+3=0|:(-1)
8x²-5x-3=0
D=25-4*8*(-3)=25+96=121
x1=(5+11)/16=16/16=1
x2=(5-11)/16=-6/16=-3/8=-0.375
Ответ: -0,375;1

Автор ответа: kolakor32

правда незнаю извени пожалуйста

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