1) X^2 - 6X + 8 = 0
D = 36 - 32 = 4 ; √ D = 2
X1 = ( 6 + 2 ) : 2 = 4
X2 = ( 6 - 2 ) : 2 = 2
ОТВЕТ 4 и 2
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2) X^2 + 4X - 12 = 0
D = 16 + 48 = 64 ; √ D = 8
X1 = ( - 4 + 8 ) : 2 = 2
X2 = ( - 4 - 8 ) : 2 = - 6
ОТВЕТ 2 и ( - 6 )
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3) X^2 + 8X + 15 = 0
D = 64 - 60 = 4 ; √ D = 2
X1 = ( - 8 + 2 ) : 2 = - 3
X2 = ( - 8 - 2 ) : 2 = - 5
ОТВЕТ ( - 3 ) и ( - 5 )