All Solutions
Page 82: Getting Started
hline
Polynomial & Type & Degree\
hlinehline
$3x^{2}+2x-1$ & trinomial &2 \
$4x-7$ & binomial & 1\
$3$ & monomial & 0\
$7+2x^{2}$ & binomial & 2\
$2xy$ & monomial & 2\
$x^{2}-3xy+y^{2}$ & trinomial & 2\
hline
end{tabular}
begin{tabular}{l|l|l|}
cline{2-3}
& Type & Degree \ cline{2-3}
a) & binomial & 1 \ cline{2-3}
b) & monomial & 0 \ cline{2-3}
c) & binomial & 2 \ cline{2-3}
d) & monomial & 2 \ cline{2-3}
e) & trinomial & 2 \ cline{2-3}
end{tabular}
end{table}
$$
begin{align*}
(2x+3)+(7x-5)&=2x+3+7x-5 tag{text{clear the parentheses }}\
&=2x+7x+3-5 tag{text{group the like terms}}\
&=9x-2\
end{align*}
$$
$$
begin{align*}
(4x^{2}-7x+1)-(2x^{2}-3x+10)&=4x^{2}-7x+1-2x^{2}+3x-10 tag{text{clear the parentheses and shange sign into second parentheses}}\
&=4x^{2}-2x^{2}-7x+3x+1-10 tag{text{group like terms}}\
&=2x^{2}-4x-9\
end{align*}
$$
$$
begin{align*}
(2x-3)(4x+5)&=\
&=8x^{2}+10x-12x-15 tag{text{distribute each term of the first polynomial to every term of the second polynomial. }}\
&=8x^{2}-2x-15
end{align*}
$$
$$
begin{align*}
(2x-1)^{2}&=(2x-1)(2x-1)\
&=4x^{2}-2x-2x+1\
&=4x^{2}-4x+1\
end{align*}
$$
b) $2x^2-4x-9$
c) $8x^2-2x-15$
d) $4x^2-4x+1$
$textbf{Factoring}$ a polynomial means to write it as a product of two or more polynomials.
$textbf{Expanding}$ a means multiply using the distributive property.
$(3x+1)(2x-3)overset{text{expanding$longrightarrow$ }}= 6x^{2}-7x-3$
and:
$$
(3x+1)(2x-3)underset{text{$longleftarrow$ factoring}}= 6x^{2}-7x-3
$$
2xy^3
,$ the given expression, $6xy^3-8x^2y^3
,$ is equivalent to
$$
begin{align*}
&
2xy^3(3-4x)
.end{align*}
$$
expression
$$
begin{align*}
a^2-7a+10
end{align*}
$$
has $c=
10$ and $b=
-7
.$
The two numbers with a product of $c$ and a sum of $b$ are $left{
-2,-5
right}.$ Using these two numbers, the
expression
above is equivalent to
$$
begin{align*}
(x-2)(x-5)
.end{align*}
$$
$$
begin{align*}
12n^2+7n-10
end{align*}
$$
has $ac=
12(-10)=-120$ and $b=
7
.$
The two numbers with a product of $c$ and a sum of $b$ are $left{
-8,15
right}.$ Using these $2$ numbers to decompose the middle term of the trinomial expression above results to
$$
begin{align*}
12n^2-8n+15n-10
.end{align*}
$$
Grouping the first and second terms and the third and fourth terms, the given expression is equivalent to
$$
begin{align*}
(12n^2-8n)+(15n-10)
.end{align*}
$$
Factoring the $GCF$ in each group results to
$$
begin{align*}
4n(3n-2)+5(3n-2)
.end{align*}
$$
Factoring the $GCF=
(3n-2)$ of the entire expression above results to
$$
begin{align*}
(3n-2)(4n+5)
.end{align*}
$$
expression,
$9-25x^2
,$ is equivalent to
$$
begin{align*}
&
(3)^2-(5x)^2
\&=
(3+5x)(3-5x)
.end{align*}
$$
expression
$$
begin{align*}
x^2+5x+8
end{align*}
$$
has $c=
8$ and $b=
5
.$
There are no two integers whose product is $8$ and whose sum is $5.$ Hence, the given expression is not factorable using integers.
expression
$$
begin{align*}
y^2-5y-36
end{align*}
$$
has $c=
-36$ and $b=
-5
.$
The two numbers with a product of $c$ and a sum of $b$ are $left{
-9,4
right}.$ Using these two numbers, the
expression
above is equivalent to
$$
begin{align*}
(y-9)(y+4)
.end{align*}
$$
b) $(x-2)(x-5)$
c) $(3n-2)(4n+5)$
d) $(3+5x)(3-5x)$
e) not factorable
f) $(y-9)(y+4)$
12
,$ the given expression, $dfrac{3}{4}+dfrac{1}{6}
,$ simplifies to
$$
begin{align*}
&
dfrac{3}{4}cdotdfrac{3}{3}+dfrac{1}{6}cdotdfrac{2}{2}
\\&=
dfrac{9}{12}+dfrac{2}{12}
\\&=
dfrac{9+2}{12}
\\&=
dfrac{11}{12}
.end{align*}
$$
10
,$ the given expression, $dfrac{-2}{5}-dfrac{1}{10}
,$ simplifies to
$$
begin{align*}
&
dfrac{-2}{5}cdotdfrac{2}{2}-dfrac{1}{10}
\\&=
dfrac{-4}{10}-dfrac{1}{10}
\\&=
dfrac{-4-1}{10}
\\&=
dfrac{-5}{10}
\\&=
-dfrac{1}{2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
left( dfrac{cancel3(-4)}{cancel5(5)} right)left( dfrac{cancel5(-2)}{cancel3(3)} right)
\\&=
left( dfrac{-4}{5} right)left( dfrac{-2}{3} right)
.end{align*}
$$
Multiplying the numerators and the denominators, the expression above is equivalent to
$$
begin{align*}
dfrac{8}{15}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
left( dfrac{4}{3} right)cdotleft( dfrac{15}{-2} right)
.end{align*}
$$
Cancelling the common factors between the numerator and the denominator, the expression above is equivalent to
$$
begin{align*}
&
left( dfrac{cancel2(2)}{cancel3} right)cdotleft( dfrac{cancel3(5)}{cancel2(-1)} right)
\\&=
left( dfrac{2}{1} right)left( dfrac{5}{-1} right)
.end{align*}
$$
Multiplying the numerators and the denominators, the expression above is equivalent to
$$
begin{align*}
&
dfrac{10}{-1}
\\&=
-10
.end{align*}
$$
b) $-dfrac{1}{2}$
c) $dfrac{8}{15}$
d) $-10$
,$ is equivalent to
$$
begin{align*}
&
left( dfrac{cancel2x^2}{3} right)left( dfrac{5x^3}{cancel2(2)} right)
\\&=
left( dfrac{x^2}{3} right)left( dfrac{5x^3}{2} right)
.end{align*}
$$
Multiplying the numerators and the denominators, the expression above is equivalent to
$$
begin{align*}
&
dfrac{5x^{2+3}}{6}
\\&=
dfrac{5x^{5}}{6}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
left( dfrac{3x}{2} right)cdotleft( dfrac{5}{x^3} right)
.end{align*}
$$
Cancelling the common factors between the numerator and the denominator, the expression above is equivalent to
$$
begin{align*}
&
left( dfrac{3cancel{x}}{2} right)cdotleft( dfrac{5}{cancel{x(x^2)}} right)
\\&=
left( dfrac{3}{2} right)left( dfrac{5}{x^2} right)
.end{align*}
$$
Multiplying the numerators and the denominators, the expression above is equivalent to
$$
begin{align*}
&
dfrac{15}{2x^2}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
(2)(4)x^{2+1}y^{3+2}
\&=
8x^{3}y^{5}
.end{align*}
$$
,$ is equivalent to
$$
begin{align*}
&
dfrac{25}{5}x^{5-2}y^{3-1}
\\&=
5x^{3}y^{2}
.end{align*}
$$
b) $dfrac{15}{2x^2}$
c) $8x^3y^5$
d) $5x^{3}y^{2}$
,$ is defined. Hence, the domain is the set of all real numbers.
,$ is defined. Hence, the domain is the set of all real numbers.
,$ should be nonnegaative. That is
$$
begin{align*}
xge0
.end{align*}
$$
Hence, the domain is ${x|xge0}
.$
,$ should not be zero. That is
$$
begin{align*}
xne0
.end{align*}
$$
Hence, the domain is ${x|xne0}
.$
,$ should not be zero. That is
$$
begin{align*}
x-4&ne0
\
x&ne4
.end{align*}
$$
Hence, the domain is ${x|xne4}
.$
,$ should be nonnegative. That is,
$$
begin{align*}
x+10ge0
\
xge-10
.end{align*}
$$
Hence, the domain is ${x|xge-10}
.$
b) domain: all readomain: l numbers
c) domain: ${x|xge0}$
d) domain: ${x|xne0}$
e) domain: ${x|xne4}$
f) domain: ${x|xge-10}$
An expression that takes the form $a_0x^n+a_1x^{n-1}+a_2x^{n-2}+…+a_n
,$ where all the exponents are nonnegative integers and all the coefficients are real numbers.
Characteristics:
The exponents are nonnegative integers.
Examples:
$5$,
$x^2+1$,
$$
dfrac{1}{3}x^2+pi x
$$
Non-examples:
$dfrac{5}{x}$,
$x^{-5}$,
$sqrt{x}$.