SOLUTION: True or False? A number k is a root of P(x) if and only if the remainder, when dividing P(x) by x+k, equals zero.

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Question 1195036: True or False?

A number k is a root of P(x) if and only if the remainder, when dividing P(x) by x+k, equals zero.

Found 2 solutions by math_tutor2020, ikleyn:
Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

Answer: False

Why is this? Because the x+k should be x-k
The remainder of P(x)/(x-k) is P(k)

If the remainder is 0, then (x-k) is a factor of P(x)
We can say
P(x) = (x-k)Q(x)
where Q is the quotient polynomial.

Further Reading about the remainder theorem can be found here
https://www.purplemath.com/modules/remaindr.htm
https://www.mathsisfun.com/algebra/polynomials-remainder-factor.html

Answer by ikleyn(52852) About Me  (Show Source):
You can put this solution on YOUR website!
.
True or False?

A number k is a root of P(x) if and only if the remainder, when dividing P(x) by x+k, equals zero.
~~~~~~~~~~~~~~~~~~~~~~


As written in the post,  the statement is  FALSE.

The correct statement is  THIS

    A number k is a root of P(x) if and only if 
    the remainder, when dividing P(x) by x-k, equals zero.


        ***********************************
                It is the  Remainder  Theorem.
        ***********************************


   Theorem   (the remainder theorem)
   1. The remainder of division the polynomial  f%28x%29  by the binomial  x-a  is equal to the value  f%28a%29  of the polynomial.
   2. The binomial  x-a  divides the polynomial  f%28x%29  if and only if the value of  a  is the root of the polynomial  f%28x%29,  i.e.  f%28a%29+=+0.
   3. The binomial  x-a  factors the polynomial  f%28x%29  if and only if the value of  a  is the root of the polynomial  f%28x%29,  i.e.  f%28a%29+=+0.


See the lessons
    - Divisibility of polynomial f(x) by binomial x-a and the Remainder theorem
    - Solved problems on the Remainder thoerem
in this site.


Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic
"Divisibility of polynomial f(x) by binomial (x-a). The Remainder theorem".

Save the link to this online textbook together with its description

Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson

to your archive and use it when it is needed.