• Home
  • Textbooks
  • Precalculus
  • Roots of Polynomial Equations

Precalculus

David Cohen, Theodore B. Lee, David Sklar

Chapter 13

Roots of Polynomial Equations - all with Video Answers

Educators


Section 1

Division of Polynomials

01:50

Problem 1

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{2}-8 x+4}{x-3}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:55

Problem 2

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{3}-4 x^{2}+x-2}{x-5}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:24

Problem 3

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{2}-6 x-2}{x+5}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:09

Problem 4

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{3 x^{2}+4 x-1}{x-1}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:52

Problem 5

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{6 x^{3}-2 x+3}{2 x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:16

Problem 6

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{4}-4 x^{3}+6 x^{2}-4 x+1}{x-1}$$

Amy Jiang
Amy Jiang
Numerade Educator
03:17

Problem 7

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{5}+2}{x+3}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:56

Problem 8

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{4 x^{3}-x^{2}+8 x-1}{x^{2}-x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
03:23

Problem 9

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{6}-64}{x-2}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:48

Problem 10

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{x^{6}+64}{x-2}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:14

Problem 11

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{5 x^{4}-3 x^{2}+2}{x^{2}-3 x+5}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:10

Problem 12

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{8 x^{6}-36 x^{4}+54 x^{2}-27}{2 x^{2}-3}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:12

Problem 13

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{3 y^{3}-4 y^{2}-3}{y^{2}+5 y+2}$$

Amy Jiang
Amy Jiang
Numerade Educator
03:43

Problem 14

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{4 y^{4}-y^{3}+2 y-1}{2 y^{2}-3 y-4}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:12

Problem 15

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{t^{4}-4 t^{3}+4 t^{2}-16}{t^{2}-2 t+4}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:06

Problem 16

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{2 f^{5}-6 t^{4}-t^{2}+2 t+3}{t^{3}-2}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:24

Problem 17

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{z^{5}-1}{z-1}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:22

Problem 18

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{1+z+z^{2}+z^{3}}{1+z+z^{2}}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:46

Problem 19

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{a x^{2}+b x+c}{x-r}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:54

Problem 20

Use long division to find the quotients and the remainders. Also, write each answer in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2) in the text.
$$\frac{a x^{3}+b x^{2}+c x+d}{x-r}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:29

Problem 21

In Exercises $21-40$, use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{2}-6 x-2}{x-5}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:04

Problem 22

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{3 x^{2}+4 x-1}{x-1}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:06

Problem 23

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{4 x^{2}-x-5}{x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
00:57

Problem 24

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{2}-1}{x+2}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:29

Problem 25

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{6 x^{3}-5 x^{2}+2 x+1}{x-4}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:19

Problem 26

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{4}-4 x^{3}+6 x^{2}-4 x+1}{x-1}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:07

Problem 27

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{3}-1}{x-2}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:10

Problem 28

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{3}-8}{x-2}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:51

Problem 29

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{5}-1}{x+2}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:16

Problem 30

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{3}-8 x^{2}-1}{x+3}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:44

Problem 31

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{4}-6 x^{3}+2}{x+4}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:37

Problem 32

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{3 x^{3}-2 x^{2}+x+1}{x-\frac{1}{2}}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:22

Problem 33

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{3}-4 x^{2}-3 x+6}{x-10}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:20

Problem 34

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{1+3 x+3 x^{2}+x^{3}}{x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:21

Problem 35

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{3}-x^{2}}{x+5}$$

Amy Jiang
Amy Jiang
Numerade Educator
03:07

Problem 36

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{5 x^{4}-4 x^{3}+3 x^{2}-2 x+1}{x+\frac{1}{2}}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:11

Problem 37

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{14-27 x-27 x^{2}+54 x^{3}}{x-\frac{2}{3}}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:58

Problem 38

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{14-27 x-27 x^{2}+54 x^{3}}{x+\frac{2}{3}}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:37

Problem 39

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
$$\frac{x^{4}+3 x^{2}+12}{x-3}$$

Amy Jiang
Amy Jiang
Numerade Educator
03:02

Problem 40

Use synthetic division to find the quotients and remainders. Also, in each case, write the result of the division in the form $p(x)=d(x) \cdot q(x)+R(x),$ as in equation ( 2 ) in the text.
(a) $\frac{x^{4}-16}{x-2}$
(b) $\frac{x^{4}+16}{x+2}$

Amy Jiang
Amy Jiang
Numerade Educator
02:16

Problem 41

Each expression has the form $x^{n}-a^{n}$ Write each expression as a product of two factors (as in the box on page 924 ).
$$x^{5}-32$$

Amy Jiang
Amy Jiang
Numerade Educator
00:46

Problem 42

Each expression has the form $x^{n}-a^{n}$ Write each expression as a product of two factors (as in the box on page 924 ).
$$y^{6}-1$$

Amy Jiang
Amy Jiang
Numerade Educator
00:53

Problem 43

Each expression has the form $x^{n}-a^{n}$ Write each expression as a product of two factors (as in the box on page 924 ).
$$z^{4}-81$$

Amy Jiang
Amy Jiang
Numerade Educator
01:52

Problem 44

Each expression has the form $x^{n}-a^{n}$ Write each expression as a product of two factors (as in the box on page 924 ).
$$x^{7}-y^{7}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:30

Problem 45

Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{6 x^{2}-8 x+1}{3 x-4}$$
Hint: Divide both numerator and denominator by $3 .$ (Why?)

Amy Jiang
Amy Jiang
Numerade Educator
01:51

Problem 46

Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{4 x^{3}+6 x^{2}-6 x-5}{2 x-3}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:31

Problem 47

Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{6 x^{3}+1}{2 x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:08

Problem 48

Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{5 x^{3}-3 x^{2}+1}{3 x+1}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:35

Problem 49

When $x^{3}+k x+1$ is divided by $x+1,$ the remainder is $-4 .$ Find $k$

Amy Jiang
Amy Jiang
Numerade Educator
01:02

Problem 50

(a) Show that when $x^{3}+k x+6$ is divided by $x+3,$ the remainder is $-21-3 k$
(b) Determine a value of $k$ such that $x+3$ will be a factor of $x^{3}+k x+6$

Amy Jiang
Amy Jiang
Numerade Educator
01:13

Problem 51

When $x^{2}+2 p x-3 q^{2}$ is divided by $x-p$, the remainder is zero. Show that $p^{2}=q^{2}$

Amy Jiang
Amy Jiang
Numerade Educator
01:49

Problem 52

Given that $x-3$ is a factor of $x^{3}-2 x^{2}-4 x+3,$ solve the equation $x^{3}-2 x^{2}-4 x+3=0$

Amy Jiang
Amy Jiang
Numerade Educator
00:53

Problem 53

The process of synthetic division applies equally well when some or all of the coefficients are nonreal complex numbers. In Exercises $53-56$, use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{x^{2}-4 x+1}{x-i}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:31

Problem 54

The process of synthetic division applies equally well when some or all of the coefficients are nonreal complex numbers. Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{x^{3}-2 x^{2}-4}{x-3 i}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:11

Problem 55

The process of synthetic division applies equally well when some or all of the coefficients are nonreal complex numbers. Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{x^{2}-2 x+2}{x-(1+i)}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:21

Problem 56

The process of synthetic division applies equally well when some or all of the coefficients are nonreal complex numbers. Use synthetic division to determine the quotient $q(x)$ and the remainder $R(x)$ in each case.
$$\frac{x^{3}-x^{2}+4 x-4}{x+2 i}$$

Amy Jiang
Amy Jiang
Numerade Educator
01:20

Problem 57

Given that the identity $f(x)=d(x) \cdot q(x)+R(x)$ holds for the following polynomials, evaluate $f(\sqrt{3})$ Hint (of sorts): There's an easy way and a tedious way.
$$\begin{array}{ll}
f(t)=\ell-3 t^{4}+2 t^{3}-5 t^{2}+6 t-7 & d(t)=t-4 \\
q(t)=t^{4}+t^{3}+6 t^{2}+19 t+82 & R(t)=321
\end{array}$$

Amy Jiang
Amy Jiang
Numerade Educator
00:55

Problem 58

Given that the identity $f(t)=d(t) \cdot q(t)+R(t)$ holds for the following polynomials, evaluate $f(4)$
$$\begin{aligned}
&f(t)=t^{5}-3 t^{4}+2 t^{3}-5 t^{2}+6 t-7 \quad d(t)=t-4\\
&q(t)=t^{4}+t^{3}+6 t^{2}+19 t+82 \quad R(t)=321
\end{aligned}$$

Amy Jiang
Amy Jiang
Numerade Educator
02:13

Problem 59

Find the remainder when $t^{5}-5 a^{4} t+4 a^{5}$ is divided by $t-a$

Amy Jiang
Amy Jiang
Numerade Educator
00:29

Problem 60

When $f(x)$ is divided by $(x-a)(x-b),$ the remainder is $A x+B .$ Apply the division algorithm to show that
$$A=\frac{f(a)-f(b)}{a-b} \quad \text { and } \quad B=\frac{b f(a)-a f(b)}{b-a}$$

James Kiss
James Kiss
Numerade Educator