Math Is Fun Forum

unique

Member

Registered: 2006-10-04

Posts: 419

in my view it seems right

use the remainder theorem to evaluate 4x^3 + 2xx^2 + 3 + 1 , when x = -2

4(-2)^3 + 2(-2)^2 + 3(-2) + 1
-32 + 8 + (-6) + 1
-32 + 8 - 6 + 1
-24 - 6 + 1
-30 + 1
-29

---

Desi
Raat Key Rani !

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: in my view it seems right

I'm assuming there's a typo in your top line and that the 3 should be 3x. If so, then you have the right answer, but are using the wrong method.

To find the answer using the remainder theorem, you need to divide (4x³ + 2x² + 3x + 1) by (x+2). The remainder of that will be the value of the function at x=-2, which as you've already found, is -29.

---

Why did the vector cross the road?
It wanted to be normal.