A remainder theorem question.
Favorites|Homepage
Subscriptions | sitemap
HOME > Mathematics > A remainder theorem question.

A remainder theorem question.

[From: ] [author: ] [Date: 11-04-29] [Hit: ]
f(2)=f(1)+5 , 20+4a=6+a+5 , 3a=-9 , a=-3 .......
I'm doing this question as part of some AS Maths revision, and keep getting -10 although apparently the answer is -3.

The remainder when 2x^3 + ax^2 + 4 is divided by x-2 is five more than when it is divided by x-1. Find a.

I'm pretty confident on the remainder theorem so it's probably just a silly mistake I'm making that I'm too tired to spot for myself!

My working is as follows anyway:

(x-2) --> f(2)

16 + 4a + 4 = 5r
20 + 4a = 5r

(x-1) --> f(1)
2 + a + 4 = r
6 + a = r

Solve simultaneously:

20 + 4a = 5(6 + a)
20 + 4a = 30 + 5a
4a = 10 + 5a
0 = 10 + a
a = -10

Help!

-
5 more means add 5 not multiply by 5 . f(2)=f(1)+5 , 20+4a=6+a+5 , 3a=-9 , a=-3 .
1
keywords: remainder,theorem,question,A remainder theorem question.
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .