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October 16th, 2014, 08:00 PM  #1 
Senior Member Joined: Aug 2014 From: Mars Posts: 101 Thanks: 9  Do I not list simplest form?
I'm getting into quadratic equations and final answers are coming in the form of $\displaystyle 0=8y^2+5y$ instead of $\displaystyle 0=8y+5$ which both come out to be the same answer. So is the author leaving out a process?

October 16th, 2014, 08:17 PM  #2 
Senior Member Joined: Jul 2014 From: भारत Posts: 1,178 Thanks: 230  The latter is the simplification of the former. $\displaystyle \textbf{Transpose } (5y) $ to the left and divide the entire equation by y. Then transpose 5 to the right again, you get the same. Last edited by skipjack; November 22nd, 2014 at 03:02 AM. 
October 16th, 2014, 08:45 PM  #3 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,879 Thanks: 1087 Math Focus: Elementary mathematics and beyond 
0 = 8y + 5 effectively omits the solution y = 0.

October 16th, 2014, 09:32 PM  #4 
Senior Member Joined: Aug 2014 From: Mars Posts: 101 Thanks: 9 
I thank you guys for all your help, but I sometimes get the feeling you love trolling everyone. What? What? 
October 17th, 2014, 01:22 AM  #5 
Math Team Joined: May 2013 From: The Astral plane Posts: 1,889 Thanks: 769 Math Focus: Wibbly wobbly timeywimey stuff. 
What trolling? $\displaystyle 8y^2 + 5y = 0$ $\displaystyle y(8y + 5) = 0$ We have the two possibilities: $\displaystyle y = 0 \text{ or } 8y + 5 = 0$ So we have two solutions: $\displaystyle y = 0 \text{ and }y = \frac{5}{8}$ The equation $\displaystyle 8y + 5 = 0$ only has one solution $\displaystyle y = \frac{5}{8}$ So what greg1313 said is perfectly accurate...The difference between the two equations is the existence of the y = 0 solution. How is this trolling? Dan 
October 17th, 2014, 02:11 AM  #6 
Senior Member Joined: Aug 2014 From: Mars Posts: 101 Thanks: 9 
The question is, if I was asked to put this in simplest form, which one would be correct? Neither of your responses said this. Though I do like how it is pointed out that there is a third option of zero on one of the problems. 
October 17th, 2014, 02:22 AM  #7 
Math Team Joined: May 2013 From: The Astral plane Posts: 1,889 Thanks: 769 Math Focus: Wibbly wobbly timeywimey stuff. 
They are both in simplest form as they both have a different set of solutions. They are not the same equation. Dan 

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