SOLUTION: what is the remainder when P(x)=x^(2)+5 is divided by (x+1)

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Question 1205720: what is the remainder when P(x)=x^(2)+5 is divided by (x+1)

Found 2 solutions by Theo, ikleyn:
Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
x^2 + 5 is equal to (x + 1) * (x - 1) with a remainder of 6.

(x + 1) * (x - 1) = x^2 - 1
add the remainder of 6 to that and you get x^2 + 5.

the divisor is x + 1
the dividend is x^2 + 5
the quotient is x - 1 with a remainder of 6.






Answer by ikleyn(52776)   (Show Source): You can put this solution on YOUR website!
.
what is the remainder when P(x)=x^(2)+5 is divided by (x+1)
~~~~~~~~~~~~~~~~~~~~~~


        I will show you two ways of solving this problem.


       First way: using the remainder theorem


According to the Remainder theorem, the remainder of division any polynomial P(x)
by a binomial (x-a), where "a" is a real (or integer) number, is the value 
of the polynomial P(x) at x= a, i.e. P(a).


In this problem, a= -1, so, according to the Remainder theorem, the remainder 
of division P(x) = x^2+5 by (x+1) is P(-1) = (-1)^2 + 5 = 6.


ANSWER.  The remainder of division P(x) = x^2+5  by  (x+1)  is  6.



       Second way: using explicit division via grouping


Using grouping, we can write

    P(x) =  =  +  = x(x+1)  + (-x-1) + 1 + 5 = x(x+1) - (x+1) + 6 = 

         = (x+1)*(x-1) + 6.


It shows that when P(x) is divided by (x+1), the quotient is (x-1) and the remainder is 6.


Thus the ANSWER is the same as in the first solution above.

Solved in two ways for your better understanding.

--------------

Surely, there is third way, which is direct long division of polynomials.

This method is straightforward and purely mechanical procedure - therefore,
I do not say more about it and even do not show it here.



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