polynomial Question !

2009-12-26 10:47 pm
When a P ( X) is divided by x - 2 , the R is 3 . when it is divided by x -3 , the R is 2 .Find R when P (x )is divided by (x-2)(x-3)


thx !!

回答 (1)

2009-12-26 10:53 pm
✔ 最佳答案
Let P(x) = Q(x)(x - 2)(x - 3) + Ax + B
Remainder theorem
P(2) = Q(2)(2 - 2)(2 - 3) + 2A + B = 3 => 2A + B = 3...(1)
P(3) = Q(3)(2 - 3)(3 - 3) + 3A + B = 2 => 3A + B = 2...(2)
(2) - (1) => A = -1
Sub into (1), 2(-1) + B = 3 => B = 5
Therefore P(x) = Q(x)(x - 2)(x - 3) - x + 5
The remainder when P(x) is divided by (x - 2)(x - 3) is - x + 5


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