We'll expand the square from
f(x):
f(x) = x^2 - 2x + 1 + x^5 + x^4 - x^2 +
2x
We'll eliminate like
terms:
f(x) = x^5 + x^4 +
1
We'll recognize in expression of g(x) the binomial raised
to cube:
g(x) = (x+1)^3
Since
the divisor is of 3rd order, the reminder has to be of 2nd
order.
r=ax^2 + bx + c
We 'll
write the reminder theorem:
f=g*q + r, where q is the
quotient of the division.
We notice that x=1 is a multiple
root of the polynomial g.
f(-1)=g(-1)*q(-1) +
r(-1)
By substituting the value x=-1 into all polynomials,
we'll obtain:
f(-1)= (-1)^5 + (-1)^4 +
1
f(-1)=-1+1+1
f(-1)=1
g(-1)=
(-1+1)^3=0
r(-1)=a-b+c
So,
we'll have:
1=0*q(-1) +
a-b+c
1=a-b+c
Because of the
fact that x=-1 is a multiple root, it will cancel the first derivative of the
expression: f=g*c + r
f' =(g*c)' +
r'
5x^4 +4 x^3=3*(x+1)^2*q+(x+1)^3*q' +2*ax+
b
By substituting the value x=-1 into all polynomials,
we'll
obtain:
5-4=-2*a+b
1=-2*a+b
We'll
calculate the first derivative of the expression
5x^4 +4
x^3=3*(x+1)^2*q+(x+1)^3*q' +2*ax+ b
(5x^4 +4
x^3)'=(3*(x+1)^2*q+(x+1)^3*q' +2*ax+ b)'
5*4* x^3 + 4*3*
x^2=6*(x+1)*q+3*(x+1)^2*q'+3*(x+1)^2*q'+(x+1)^3*q"+2a
By
substituting the value x=-1 into all polynomials, we'll
obtain:
-20+12=2*a
We'll
divide by 2:
a = -10 + 6
a =
-4
-2a+b=1
-2*(-4) + b =
1
b = 1 - 8
b =
-7
a-b+c =
1
-4+7+c=1
3+c=1
c=1-3
c=-2
The
reminder is: r(x) = -4x^2 - 7x - 2.
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