Maths ERGENT HW!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!20pts

2007-10-28 6:31 pm
a) Write down the highest possible degree of the remainder when a polynomial P(x) is divided by (x-1)(x+2)
b) It is given that when P(x) is divided by x-1 and x+2, the remainders are -4 and -28 respectively. Find the remainder when P(x) is divided by (x-1)(x+2)

回答 (1)

2007-10-28 6:37 pm
✔ 最佳答案
a. The highest possible degree of the remainder is 1



b. Let P(x) = (x - 1)(x + 2)Q(x) + (ax + b)

where Q(x) is a polynomial

a and b are constants


By remainder theorem,

f(1) = -4

So, a + b = -4

f(-2) = -28

So, -2a + b = -28


Solving the two equations,

a = 8

b = -12


So, when P(x) is divided by (x - 1)(x + 2),

the remainder is 8x - 12
參考: Myself~~~


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