Vatazovuc
6 год назад
X(x+2)(x+3)(x+5) = 72 помогите пож
ОТВЕТЫ
Ерофеевич
Jun 30, 2019
X(x+5)(x+2)(x+3) = 72
(x² + 5x)(x² + 5x + 6) = 72
x² + 5x = t
t(t+6) = 72
t²+ 6t - 72 = 0
D = 36 + 288 = 324 = 18²
t1 = (-6-18)/2 = -12
t2 = (-6+18)/2 = 6
x² + 5x = -12
x² + 5x + 12 = 0
D = 25 - 48 lt; 0
x² + 5x = 6
x² + 5x - 6 = 0
D = 25 + 24 = 49 = 7²
x1 = (-5-7)/2 = -6
x2 = (-5+7)/2 = 1
Ответ: -6 и 1
(x² + 5x)(x² + 5x + 6) = 72
x² + 5x = t
t(t+6) = 72
t²+ 6t - 72 = 0
D = 36 + 288 = 324 = 18²
t1 = (-6-18)/2 = -12
t2 = (-6+18)/2 = 6
x² + 5x = -12
x² + 5x + 12 = 0
D = 25 - 48 lt; 0
x² + 5x = 6
x² + 5x - 6 = 0
D = 25 + 24 = 49 = 7²
x1 = (-5-7)/2 = -6
x2 = (-5+7)/2 = 1
Ответ: -6 и 1
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