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. .(
.
.
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: ()
a2 −b2 = (a −b )(a + b ) ()
: ()
()
( ).a3 − b3 = (a − b) a2 + ab + b2
:
( ).a3 + b3 = (a + b) a2 − ab + b2
. 6x 4 + 3x 3 + 3x 2
( )6x 4 + 3x 3 + 3x2 = 3x2 2x2 + x + 1
. 1 − 4 × 1× 2 = −7 < 0 2x2 + x + 1
.
. x12 − 212 ( )
( )( )x12 − 212 = x 6 − 26 x 6 + 26
= (x 3 − 23 )(x 3 + 23 )(x2 + 22 )(x 4 − 4x 2 + 16 )
= (x − 2)(x 2 + 2x + 4 )(x + 2)(x 2 − 2x + 4 )
(x2 + 4 )(x 4 − 4x2 + 16)