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( )x 3 + 2x 2 + ax + b = (x + c) x2 + x + 2
= x 3 + (c + 1)x 2 + (c + 2)x + 2c
c+1= 2 ⇒c =1 ()
c+2 =a ⇒a = 3
b = 2c ⇒ b = 2
.a −b = 3 − 2 = 1
:( )
( )81x 4 − 16 = 9x 2 + 4 (3x + 2)(3x − 2)
.a −b + c + d −e + f = 9 − 4 + 3 + 2 − 3 − 2 = 5 ()
:( )
6x 4 − 3x 3 − 4x 2 + x =
x(x − 1)x − −3 + 33 x − −3 − 33
12 12
a + b + c + d = 0 + 1 + −3 + 33 + −3 − 33
12 12
= 1− 3 − 3 = 1−1 = 1
12 12 22
:( ) ()
x 4 − 10x 2 + 9 = (x 2 − 9)(x 2 − 1)
= (x − 3)(x + 3)(x − 1)(x + 1)
x4 = −1 x3 = 1 x2 = −3 x1 = 3