# Factoring

(1) GCF factoring. Factoring out the Greatest Common Factor is, as we know, simply an application of
the distributive law: ab+ac = a(b+c). We factor out the largest numerical divisor of all the coefficients (the GCF
of the coefficients) and the least power on any common variable – remembering that we end up with the same
number of terms inside the parentheses as we had in the original expression. For example,
factors into . GCF factoring is the most primitive factoring and the easiest. ALWAYS do any
GCF factoring FIRST in any problem where factoring is needed.

(2) Special Products factoring.

(a) Difference of squares. The difference of two squares, , factors into a product of
binomial conjugates : “the first plus the second times , the first minus the second” . For
example, . The sum of two squares, , DOES
NOT FACTOR knowing what we know so far. In general, if an expression does not factor, it is called prime.

(b) Perfect Square Trinomials. Perfect square trinomials are the result of squaring binomial
sums and differences. Each of the ex pressions to the right of the “=” be low is a perfect square trinomial.

Hence, if we have a trinomial with the squares of two objects on the “outside” and either twice their product or the
negation of twice their product “in the middle,” we have a perfect square trinomial:

For example, and more complicated, but identical in form,
we have .

(3) Group and Hope . This is a very specialized method that can be tried if you have four terms with no
common
factor, such as . The idea is to group the terms into two sets of two, factor each
group and hope something pops up that is useful. We’ll look at the three different ways of grouping this
expression and see what happens:

 grouping terms 1&2 and 3&4 factor each group and magic! factor out(x-2b) grouping terms 1&3 and 2&4 factor each group and magic again! factor out (x+5) grouping terms 1&4 and 2&3 yuk, no luck here

If the Group and Hope method works, you will be able to factor the expression in at least two of the three ways
you can group its terms. So, if one grouping doesn’t work, try another; if that also doesn’t work, then this method
fails.

(4) Sum and Difference of Cubes.

(5) Finally, we come to the fun one – arbitrary trinomials. Yes, we are talking about things like
which are quadratic trinomials which are not perfect squares. In order to factor such expressions, we
have to fully understand how they are formed through what you probably call FOIL but I call LipopR. Examine
carefully the form of the three products below which produce MONIC quadratic trinomials. (Recall, monic

For a and b POSITIVE :

Observe: When the trinomial’s CONSTANT is POSITIVE (cases (A) and (B)), the two binomials have the same
middle sign. In that case, if the linear coefficient is positive (case (A)), the binomial middle signs are “ + ”; and if
the linear coefficient is negative (case(B)), the binomial middle signs are “ – “. The only time the binomial
middle signs are opposite of each other is when the trinomial’s CONSTANT is NEGATIVE (case (C)). Thus, we
know that if the following trinomials factor, then the factorization has the stated form.

We also observe that the trinomial’s constant (ab)is the product of the two binomial constants (a and b). So we
just have to think of all the ways the trinomial’s constant factors and check the resulting ipop (inside product +
outside product) to find the factorization.

Some examples.

 ab=6 so we have 1· 6 or 2· 3 but ipop is 5x so a + b = 5 try them:1 + 6 ≠ 5, 2 + 3 = 5 done when found 2 + 3 = 5 ab=6 so again  1· 6 or 2· 3 ipop is -7x so a +b=7 try them: 1 + 6 =7,  2 + 3 ≠ 7 done after 1 +6 =7,but I showed the other for completeness ab=6 so again 1· 6 or 2· 3 ipop is +1x so a - b =+1 try them:1-6 ≠1, 6-1≠1, 2-3≠1 3-2=1,finally
 Prev Next

Start solving your Algebra Problems in next 5 minutes!

2Checkout.com is an authorized reseller
of goods provided by Sofmath

Attention: We are currently running a special promotional offer for Algebra-Answer.com visitors -- if you order Algebra Helper by midnight of May 26th you will pay only \$39.99 instead of our regular price of \$74.99 -- this is \$35 in savings ! In order to take advantage of this offer, you need to order by clicking on one of the buttons on the left, not through our regular order page.

If you order now you will also receive 30 minute live session from tutor.com for a 1\$!

You Will Learn Algebra Better - Guaranteed!

Just take a look how incredibly simple Algebra Helper is:

Step 1 : Enter your homework problem in an easy WYSIWYG (What you see is what you get) algebra editor:

Step 2 : Let Algebra Helper solve it:

Step 3 : Ask for an explanation for the steps you don't understand:

Algebra Helper can solve problems in all the following areas:

• simplification of algebraic expressions (operations with polynomials (simplifying, degree, synthetic division...), exponential expressions, fractions and roots (radicals), absolute values)
• factoring and expanding expressions
• finding LCM and GCF
• (simplifying, rationalizing complex denominators...)
• solving linear, quadratic and many other equations and inequalities (including basic logarithmic and exponential equations)
• solving a system of two and three linear equations (including Cramer's rule)
• graphing curves (lines, parabolas, hyperbolas, circles, ellipses, equation and inequality solutions)
• graphing general functions
• operations with functions (composition, inverse, range, domain...)
• simplifying logarithms
• basic geometry and trigonometry (similarity, calculating trig functions, right triangle...)
• arithmetic and other pre-algebra topics (ratios, proportions, measurements...)

ORDER NOW!

2Checkout.com is an authorized reseller
of goods provided by Sofmath

 "It really helped me with my homework.  I was stuck on some problems and your software walked me step by step through the process..." C. Sievert, KY

 Sofmath 19179 Blanco #105-234San Antonio, TX 78258 Phone: (512) 788-5675Fax: (512) 519-1805