# Dividing polynomials.Watch

#1
Divide (x^2 +2x -4) by (X+1)

could someone help?

i know i have to write it in the form (x+1) (x^2 +px +q) +r

i used the remainder theorem to get (-5) as the remainder.
0
12 years ago
#2
(Original post by magnum)
Divide (x^2 +2x -4) by (X+1)

could someone help?

i know i have to write it in the form (x+1) (x^2 +px +q) +r

i used the remainder theorem to get (-5) as the remainder.
is that x^2 or x^3?
0
#3
x^2

?
0
12 years ago
#4
(Original post by magnum)
x^2

?
then isnt (x^2 +2x - 4) divided by (x+1) just (x+1)^2 with a r of -5?

this question out of a book or could have it been copied down wrong?

if this is the question then you cant write it in the form you need because it would be x^3 and not x^2?
0
#5
The question is out of a book...

0
#6
what about in the form of "((x+1)(x+q)+r"?
0
12 years ago
#7
(Original post by magnum)
Divide (x^2 +2x -4) by (X+1)

could someone help?

i know i have to write it in the form (x+1) (x^2 +px +q) +r

i used the remainder theorem to get (-5) as the remainder.
..........x+1.........
(x+1)|(x^2+2x-4)
.......-(x^2+x)
.................x-4
...............-(x+1)
....................-5

so (x^2+2x-4)/(x+1) = (x+1)(x+1) - 5
12 years ago
#8
x^2 + 2x - 4 = (x+1)q(x) - 5
=> x^2 + 2x + 1 = (x+1)q(x)
=> (x + 1)^2 = (x + 1)q(x)
=> q(x) = x + 1
0
12 years ago
#9
You could alwaysd try to force it to factorise, so

x^2 +2x -4 = x^2+ x +x+1 -5 = x(x+1) +1(x+1) -5 = (x+1)(x+1) -5
0
#10
ok, but is (x+1)(x+1) -5
in the form of (x+1)(x+q)+r ?
0
12 years ago
#11
(Original post by magnum)
ok, but is (x+1)(x+1) -5
in the form of (x+1)(x+q)+r ?
yes, q=1, r=-5
0
12 years ago
#12
(Original post by magnum)
ok, but is (x+1)(x+1) -5
in the form of (x+1)(x+q)+r ?
yeah so q = 1 and r = -5
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#13
Thanks all.
Much appreciated
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