is this how u do this polynomial question? (1 Viewer)

[jockrussell]

Hi, i was wondering if this is how you do the following question.

Suppose x^3– 2x^2 + a ≡ (x + 2)Q(x) + 3 where Q(x) is a polynomial.
Find the value of a.

since u dont know Q(x) id say ud have to get rid of it.
to do this i put P(-2) into the equation

so then i got
-2^3-2*-2^2+a=(-2+2)Q(-2)+3
-8-8+a=3
-16+a=3
a=19

is this right?

 

[Iruka]

Yes, 'tis the basis of the Remainder Theorem.

http://en.wikipedia.org/wiki/Polynomial_remainder_theorem

 

[tommykins]

Sub in 2, remainder is 3 then solve.

 

[midifile]

Sub in 2, remainder is 3 then solve.

Yep.

Except you sub in -2

 

[tommykins]

haha thank you