
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
April 16th, 2015, 10:57 PM  #1 
Senior Member Joined: Oct 2012 From: Live and work in Saudi but from Italy (British national) Posts: 103 Thanks: 2 Math Focus: Hoping to do something in the future.  Factoring by grouping
Hello all. Please forgive me for repeating myself. I am a beginner in maths and I am learning this in my free time because I enjoy it. I really want to understand this stuff and I have watched numerous videos and read examples, but I can't understand where I am going wrong here. I have this trinomial and I am trying to factor it by grouping: $\displaystyle 12x^221x6$ I have understood that I need to factor out the greatest common factor which is 3. So I have $\displaystyle 3(4x^27x2)$ Now I need to expand this to a 4 term polynomial so I can factor by grouping. Thus 4x(2)=8 Now I need two integers which give a product of 8 and a sum of 7 thus 1, 8 Expanding the middle term gives $\displaystyle 3[(4x^28x+x2)]$ If I factor the first group $\displaystyle (4x^28x)$ I get $\displaystyle 3[x(4X+1)]$ But the second group $\displaystyle (4x^28x)$ doesn't make sense because I get $\displaystyle 2(4x+3)$. Putting it all together, I get $\displaystyle 3[x(4x+1)2(4x+3)]$ Help! M Last edited by skipjack; April 17th, 2015 at 01:02 AM. 
April 17th, 2015, 01:13 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 18,965 Thanks: 1606 
3(4x²  8x + x  2) = 3[4x(x  2) + 1(x  2)] = 3(4x + 1)(x  2) 3(4x² + x  8x  2) = 3[x(4x + 1)  2(4x + 1)] = 3(x  2)(4x + 1) 
April 17th, 2015, 02:09 AM  #3 
Senior Member Joined: Oct 2012 From: Live and work in Saudi but from Italy (British national) Posts: 103 Thanks: 2 Math Focus: Hoping to do something in the future.  

Tags 
factoring, grouping 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Grouping Symbols  NoOp  Algebra  3  October 11th, 2012 12:39 AM 
Help with grouping polynomial  DPXJube  Algebra  2  February 10th, 2012 09:15 AM 
grouping x^3x^2+x1  Peacelyk  Algebra  3  January 5th, 2010 10:58 AM 
Grouping of Mumbers  bowlrig  Number Theory  3  August 7th, 2008 12:30 AM 
Help with grouping polynomial  DPXJube  Elementary Math  1  December 31st, 1969 04:00 PM 