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2.01 Factoring by Sum and Difference of Cubes
Intermediate
Algebra: One Step at a Time
Pages
126 - 130: #2, 10, 11, 18, 24, 28, 30, 32, 33, 34
Dr. Robert J. Rapalje
Seminole State College of Florida
Sanford, FL 32773
To see Section 2.01,
with explanations, examples, exercises, and answers,
click here!
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Guidelines to Factoring |
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- Common Factor
- Trinomials
- Difference of Squares;
Difference and Sum of Cubes
- Grouping
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p. 127. # 2.
Solution:
Next,
notice that this is a difference of two cubes! The
FIRST is
and
the
SECOND
is which can be written . Remember
also that the difference of two cubes factors into the product of a binomial
times a trinomial in this form, according to the formula
.
What you have is:



The trinomial CANNOT be
factored, so this is your final answer!!
p. 127. # 10.
Next, notice that this is a
difference of two cubes! The FIRST
is which
can be written and
the SECOND is
which
can be written .
Remember also that the difference of two cubes factors into the
product of a binomial times a trinomial in this form, according to the
formula .
What you have is:



The trinomial CANNOT be
factored, so this is your final answer!!
p. 127. # 11.
Next, notice that this is a
sum of two cubes! The FIRST
is which
can be written and
the SECOND is
which
can be written .
Remember also that the sum of two cubes factors into the product of a
binomial times a trinomial in this form, according to the formula
.
What you have is:



The trinomial CANNOT be
factored, so this is your final answer!!
p. 128. # 18.
Solution:
The first step is to recognize
that there is a common factor. Take out the 3 that is common to both terms.

Next, notice that what is left
the parentheses is a difference of two cubes! The FIRST
is and the
SECOND is
which can be written . Remember
also that the difference of two cubes factors into the product of a binomial
times a trinomial in this form, according to the formula
.
What you have is:



The trinomial CANNOT be
factored, so again this is your final answer!!
p. 128. # 24.
Next, notice that this is a SUM of two cubes! The FIRST is
,
which is actually and
the SECOND is which
can be written .
Remember that the sum of two cubes factors into the
product of a binomial times a trinomial in this form, according to the
formula .
What you have is:


p. 130. # 28.
Solution:
The first step is to recognize
that there is a common factor. Take out the
5 and the
x factor that are
common to both terms.
Next, notice that what is left
the parentheses is a difference of two cubes!
The FIRST is
which
can be written as and
the SECOND is
which
can be written .
Remember also that the difference
of two cubes is a binomial times a trinomial according to the formula
.
What you have is:




p. 130. # 30.
Solution:
As always, the first step is to recognize that there
is a common factor. Take out the 25
and the factor
that are common to both terms.
Next, notice that what is left
the parentheses is a sum of two cubes!
The FIRST is
which
can be written as and
the SECOND is
which
can be written .
Remember also that the sum of two
cubes is a binomial times a trinomial according to the formula
 .
What you have is:




p. 130. # 32.
Solution:
In this case, there are NO common
factors. So, try a trinomial. Notice that there are three terms, so it IS
a trinomial, which can be factored into the product of two binomials.



Notice that each of these
binomials are actually differences of two cubes, and each factors:
 
p. 130. # 34.
Solution:
This problem is easiest to factor
as a difference of two squares:



Notice that each of these
binomials are actually difference and also sum of two cubes:
You finish it:
 
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