My Math Forum Having trouble with factoring equations

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 September 2nd, 2016, 03:39 AM #1 Newbie   Joined: Apr 2016 From: England Posts: 13 Thanks: 2 Having trouble with factoring equations I've checked many videos and really can't find any covering the equations i'm stuck with. 3xsquared -15x = 0 4xsquared -8x = 0 5xsquared -12x = 0 I understand an equation with two numbers such as xsquared -9x -10 = 0 a lot more than when theres only one number in the equation, as I would normally just find the sum of -9x and the product of -10... I can't do that with just one number from what I can see. Any help would be much appreciated!
September 2nd, 2016, 04:33 AM   #2
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Quote:
 Originally Posted by WarmCustard I've checked many videos and really can't find any covering the equations i'm stuck with.
Interesting. I went to YouTube, typed in "factoring polynomials" and in less than a second got over 39,000 hits. The first two had problems just like the ones you are asking about.

 September 2nd, 2016, 05:19 PM #3 Senior Member   Joined: May 2016 From: USA Posts: 1,310 Thanks: 552 $3x^2 - 15x = 0 \implies 3x(x - 5) = 0 \implies WHAT?$ Thanks from topsquark
 September 2nd, 2016, 07:44 PM #4 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1039 It's really a quadratic: 3x^2 - 15x + 0 = 0 c = 0. Try it!
 September 3rd, 2016, 06:11 AM #5 Newbie   Joined: Sep 2016 From: Chipping Norton Posts: 5 Thanks: 0 Well you can still solve the equation... Just like JeffM1 show 3x^2-15x=0 You can take 3x out of the equation --> 3x(x-5)=0 3x=0 -> x=0; x-5=0 -> x=5 Hence x=0 or x=5 Sent from my iPhone using Tapatalk
 October 5th, 2016, 11:40 PM #6 Newbie   Joined: Jun 2016 From: india Posts: 24 Thanks: 4 3x^(2)−15x=0⟹3x(x−5)=0⟹x=0,x=5 4x^(2)− 8x=0⟹4x(x−2)=0⟹x=0,x=2 5x^(2)−12x=0⟹x(5x−12)=0⟹x=0,x=12/5 Last edited by rahuljoshi; October 5th, 2016 at 11:47 PM.
 October 18th, 2016, 03:48 PM #7 Newbie   Joined: Oct 2016 From: PA Posts: 1 Thanks: 0 How to Factor Always try to take out a GCF (biggest factor that they have in common) In this case it's 3x

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