P(x) = x^5-2x^3+3x-3.
To find
the remainder when divided by x^3-x.
x^3-x = x(x^2-1) =
(x)(x-1)(x+1).
So we can pressume that the remainder is of
the form ax^2+bx+c a second degree expression ,1degree less than x^3-x. and the quotient
is Q(x).
Therefore
,
P(x)=x^5-2x^3+3x-3 = x(x+1)(x)(x-1)Q(x) + ax^2+bx+c.
..(1)
Put x= 0 in both sides in eq
(1):
Put x = -1:
(-1)^5
- 2(-1)^3 +3(-3) -3 = (-1+1)(-1)(-1-1)Q(-1)
+a(-1)^2+b(-1)+c
-5+2-3-3 =
0+a-b+c.
-9 = a-b+c
a-b+c =
-9.......................(2)
Put x=
0
-3 = 0 +0+0+c. So c =
-3.
put x= 1:
1-2+3-3 =
0+a+b+c
-1 = a+b+c
a+b+c =
-1.............(3)
a-b+c = -
9.............(2)
Adding (1) and(2) , we get: 2a+2c = -10.
So a = -10-2c = -10 -2(-3) = -4. So a = -4/2 = -2.
Puttin
a= -2 and c = -3 in (3), we get: -2+b-3 = -1. So b = -1+5 =
4..
Therefore a=-2, b = 4 and
c=-3.
Therefore the assumed remainder ax^2+bx+c is
-2x^2+4x-3.
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