6. Consider the cubic polynomial p(x) = x^3 + x^2 - 46x + 80.

(a) Using polynomial long division, write the ratio of p(x)/(x-3) in **quotient-remainder form**, i.e. in the form q(x) + (r)/(x-3). Evaluate p(3). How does this help you check your quotient-remainder form?

GAMEMASTERX40 Feb 10, 2019

#1**0 **

x^2+4x-34 - 22/(x-3)

x-3 | x^3+x^2-46x+80

x^3 -3x^2

_______________

4x^2-46x

4x^2-12x

_____________

-34x+80

-34x+102

__________

(remainder) -22

Basically with remainder -22/(x-3) then p(3) will equal -22

See cphill's explanation/answer here for the second part:

https://web2.0calc.com/questions/what-does-this-mean_10

ElectricPavlov Feb 10, 2019

#2**+2 **

Using EP's answer of R = -22

We should get the same answer by subbing 3 inito the polynomial....so...

(3)^3 + (3)^2 - 46(3) + 80 =

27 + 9 - 138 + 80 =

116 - 138 =

-22 ......Magic !!!!!

CPhill Feb 10, 2019

#3**-3 **

Wait... I don't understand by the question: How does this help you check your quotient-remainder form?

GAMEMASTERX40 Feb 10, 2019

#4**+1 **

It helps because the "r" in r / [ x - 3 ] should be the same as evaluating P(a)

So...in the case EP divided the polynomial by x - a = x - 3 got a remainder of -22

Then....we can check whether this remainder is correct by evaluating P(a) = P(3)

Note that when we evaluated P(3)....we put 3 into the polynomial and got -22

So....we can be sure that this remainder is correct....!!!!!

Does that make sense, GM???

CPhill
Feb 10, 2019