<< Chapter < Page Chapter >> Page >
This module is from Elementary Algebra by Denny Burzynski and Wade Ellis, Jr. Factoring is an essential skill for success in algebra and higher level mathematics courses. Therefore, we have taken great care in developing the student's understanding of the factorization process. The technique is consistently illustrated by displaying an empty set of parentheses and describing the thought process used to discover the terms that are to be placed inside the parentheses.The factoring scheme for special products is presented with both verbal and symbolic descriptions, since not all students can interpret symbolic descriptions alone. Two techniques, the standard "trial and error" method, and the "collect and discard" method (a method similar to the "ac" method), are presented for factoring trinomials with leading coefficients different from 1. Objectives of this module: know how to factor a polynomial using the grouping method and when to try the grouping method.

Overview

  • Using Grouping to Factor a Polynomial
  • Knowing when to Try the Grouping Method

Using grouping to factor a polynomial

Sometimes a polynomial will not have a particular factor common to every term. However, we may still be able to produce a factored form for the polynomial.

The polynomial x 3 3 x 2 6 x 18 has no single factor that is common to every term. However, we notice that if we group together the first two terms and the second two terms, we see that each resulting binomial has a particular factor common to both terms.

The polynomial 'x cubed plus three x squared minus six x minus eighteen'. The first two terms of the polynomial have x square in common, and the last two terms of the polynomial have negative six in common.

Factor x 2 out of the first two terms, and factor 6 out of the second two terms.

x 2 ( x + 3 ) 6 ( x + 3 )

Now look closely at this binomial. Each of the two terms contains the factor ( x + 3 ) .

Factor out ( x + 3 ) .
( x + 3 ) ( x 2 6 ) is the final factorization.

x 3 + 3 x 2 6 x 18 = ( x + 3 ) ( x 2 6 )

Knowing when to try the grouping method

We are alerted to the idea of grouping when the polynomial we are considering has either of these qualities:

  1. no factor common to all terms
  2. an even number of terms

When factoring by grouping, the sign ( + or ) of the factor we are taking out will usually (but not always) be the same as the sign of the first term in that group.

Sample set a

Factor 8 a 2 b 4 4 b 4 + 14 a 2 7 .

  1. We notice there is no factor common to all terms.
  2. We see there are four terms, an even number.
  3. We see that terms 1 and 2 have + 4 b 4 in common (since the 1st term in the group is + 8 a 2 b 4 ) .
  4. We notice that the 3rd and 4th terms have + 7 in common (since the 1st term in the group is + 14 a 2 ).

    The equation eight a squared b to the fourth power minus four b to the fourth power plus fourteen a squared minus seven equals the sum of the product of four b to the fourth power and two a square minus one, and the product of seven and two a square minus 1. The two terms on the right side have two a square minus one in common. 8 a 2 b 4 4 b 4 + 14 a 2 7 = (2a 2 -1)(4b 4 +7)

Got questions? Get instant answers now!

Practice set a

Use the grouping method to factor the following polynomials.

a x a y b x b y

( a + b ) ( x + y )

Got questions? Get instant answers now!

2 a m + 8 m + 5 a n + 20 n

( 2 m + 5 n ) ( a + 4 )

Got questions? Get instant answers now!

a 2 x 3 + 4 a 2 y 3 + 3 b x 3 + 12 b y 3

( a 2 + 3 b ) ( x 3 + 4 y 3 )

Got questions? Get instant answers now!

15 m x + 10 n x 6 m y 4 n y

( 5 x 2 y ) ( 3 m + 2 n )

Got questions? Get instant answers now!

40 a b x 24 a b x y 35 c 2 x + 21 c 2 x y

x ( 8 a b 7 c 2 ) ( 5 3 y )

Got questions? Get instant answers now!

When factoring the polynomial 8 a 2 b 4 4 b 4 14 a 2 7 in Sample Set A, we grouped together terms1 and 2 and 3 and 4. Could we have grouped together terms1 and 3 and 2 and 4? Try this.
8 a 2 b 4 4 b 4 + 14 a 2 7 =

yes

Got questions? Get instant answers now!

Do we get the same result? If the results do not look precisely the same, recall the commutative property of multiplication.

Exercises

For the following problems, use the grouping method to factor the polynomials. Some polynomials may not be factorable using the grouping method.

2 a b + 3 a + 18 b + 27

( 2 b + 3 ) ( a + 9 )

Got questions? Get instant answers now!

x y 7 x + 4 y 28

Got questions? Get instant answers now!

x y + x + 3 y + 3

( y + 1 ) ( x + 3 )

Got questions? Get instant answers now!

m p + 3 m q + n p + 3 n q

Got questions? Get instant answers now!

a r + 4 a s + 5 b r + 20 b s

( a + 5 b ) ( r + 4 s )

Got questions? Get instant answers now!

14 a x 6 b x + 21 a y 9 b y

Got questions? Get instant answers now!

12 m x 6 b x + 21 a y 9 b y

3 ( 4 m x 2 b x + 7 a y 3 b y )  Not factorable by grouping

Got questions? Get instant answers now!

36 a k 8 a h 27 b k + 6 b h

Got questions? Get instant answers now!

a 2 b 2 + 2 a 2 + 3 b 2 + 6

( a 2 + 3 ) ( b 2 + 2 )

Got questions? Get instant answers now!

3 n 2 + 6 n + 9 m 3 + 12 m

Got questions? Get instant answers now!

8 y 4 5 y 3 + 12 z 2 10 z

Not factorable by grouping

Got questions? Get instant answers now!

x 2 3 x + x y 3 y

( x + y ) ( x 3 )

Got questions? Get instant answers now!

2 n 2 + 12 n 5 m n 30 m

Got questions? Get instant answers now!

4 p q 7 p + 3 q 2 21

Not factorable by grouping

Got questions? Get instant answers now!

8 x 2 + 16 x y 5 x 10 y

Got questions? Get instant answers now!

12 s 2 27 s 8 s t + 18 t

( 4 s 9 ) ( 3 s 2 t )

Got questions? Get instant answers now!

15 x 2 12 x 10 x y + 8 y

Got questions? Get instant answers now!

a 4 b 4 + 3 a 5 b 5 + 2 a 2 b 2 + 6 a 3 b 3

a 2 b 2 ( a 2 b 2 + 2 ) ( 1 + 3 a b )

Got questions? Get instant answers now!

4 a 3 b c 14 a 2 b c 3 + 10 a b c 2 35 b c 4

Got questions? Get instant answers now!

5 x 2 y 3 z + 3 x 3 y w 10 y 3 z 2 6 w x y z

y ( 5 y 2 z + 3 x w ) ( x 2 2 z )

Got questions? Get instant answers now!

a 3 b 2 c d + a b c 2 d x a 2 b x y c x 2 y

Got questions? Get instant answers now!

5 m 10 n 17 p 3 m 6 n 7 p 4 40 m 4 n 10 q t 2 + 8 p q t 2

( m 6 n 7 p 3 8 q t 2 ) ( 5 m 4 n 10 p )

Got questions? Get instant answers now!

Exercises for review

( [link] ) Simplify ( x 5 y 3 ) ( x 2 y ) .

Got questions? Get instant answers now!

( [link] ) Use scientific notation to find the product of ( 3 × 10 5 ) ( 2 × 10 2 ) .

6 × 10 3

Got questions? Get instant answers now!

( [link] ) Find the domain of the equation y = 6 x + 5 .

Got questions? Get instant answers now!

( [link] ) Construct the graph of the inequality y 2 .

A horizontal line with arrows on both ends.

A number line with arrows on each end, labeled from negative three to three in increments of one. There is a closed circle at negative two. A dark arrow is originating from this circle, and heading towrads the right of negative two.

Got questions? Get instant answers now!

( [link] ) Factor 8 a 4 b 4 + 12 a 3 b 5 8 a 2 b 3 .

Got questions? Get instant answers now!

Questions & Answers

differentiate between demand and supply giving examples
Lambiv Reply
differentiated between demand and supply using examples
Lambiv
what is labour ?
Lambiv
how will I do?
Venny Reply
how is the graph works?I don't fully understand
Rezat Reply
information
Eliyee
devaluation
Eliyee
t
WARKISA
hi guys good evening to all
Lambiv
multiple choice question
Aster Reply
appreciation
Eliyee
explain perfect market
Lindiwe Reply
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
Ezea
What is ceteris paribus?
Shukri Reply
other things being equal
AI-Robot
When MP₁ becomes negative, TP start to decline. Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 • Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 • Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Kelo
yes,thank you
Shukri
Can I ask you other question?
Shukri
what is monopoly mean?
Habtamu Reply
What is different between quantity demand and demand?
Shukri Reply
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
ok
Shukri
how do you save a country economic situation when it's falling apart
Lilia Reply
what is the difference between economic growth and development
Fiker Reply
Economic growth as an increase in the production and consumption of goods and services within an economy.but Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
Abdisa Reply
any question about economics?
Awais Reply
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50. A,Calculate quantities of x and y which maximize utility. B,Calculate value of Lagrange multiplier. C,Calculate quantities of X and Y consumed with a given price. D,alculate optimum level of output .
Feyisa Reply
Answer
Feyisa
c
Jabir
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
Gsbwnw Reply
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product
Abdureman
types of unemployment
Yomi Reply
What is the difference between perfect competition and monopolistic competition?
Mohammed
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Elementary algebra. OpenStax CNX. May 08, 2009 Download for free at http://cnx.org/content/col10614/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Elementary algebra' conversation and receive update notifications?

Ask