Объяснение:
a)
x³-2x²-6x+27=x³+3³-2x²-6x=
=(x+3)(x²-3x+9)-2x(x+3)=
=(x+3)(x²-3x+9-2x)=(x+3)(x²-5x+9)
б)
х³-2х²-6х+27=0
х³+3³-2х²-6х=0
(х+3)(х²-3х+9)-2х(х+3)=0
(х+3)(х²-3х+9-2х)=0
(х+3)(х²-5х+9)=0
х+3=0 х²-5х+9=0
х= -3 D=(-5)²-4•1•9=25-36= -11
D<0 ,нет корней
ответ: х= -3
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Объяснение:
a)
x³-2x²-6x+27=x³+3³-2x²-6x=
=(x+3)(x²-3x+9)-2x(x+3)=
=(x+3)(x²-3x+9-2x)=(x+3)(x²-5x+9)
б)
х³-2х²-6х+27=0
х³+3³-2х²-6х=0
(х+3)(х²-3х+9)-2х(х+3)=0
(х+3)(х²-3х+9-2х)=0
(х+3)(х²-5х+9)=0
х+3=0 х²-5х+9=0
х= -3 D=(-5)²-4•1•9=25-36= -11
D<0 ,нет корней
ответ: х= -3