My Math Forum Geometry problem

 Geometry Geometry Math Forum

 February 27th, 2013, 11:34 PM #1 Member   Joined: Aug 2012 Posts: 71 Thanks: 1 Geometry problem Hi, I have struggled on this question, so your help is greatly appreciated. Q: A(-2,-4) B(4,1) Using these coordinates write the equation of AB. This is my working: Gradient of AB= 5/6 y-1=5/6(x-4) y-1= 5/6x-3 1/3 Then I multiply by 6 (LCM) 5x-6y=-14 However the correct answer is 5x-6y=15 How do you get this answer? Thanks for you help
 February 27th, 2013, 11:41 PM #2 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs Re: Geometry problem I agree with you up to: $y-1=\frac{5}{6}(x-4)$ Multiply through by 6: $6y-6=5(x-4)$ $6y-6=5x-20$ $5x-6y=14$ You can verify this is correct by substituting the coordinates from the given points into the equation.
 February 27th, 2013, 11:48 PM #3 Member   Joined: Aug 2012 Posts: 71 Thanks: 1 Re: Geometry problem Thanks very much. I used the other given coordinate and got the same answer. So is this just an error in my textbook?
 February 27th, 2013, 11:53 PM #4 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs Re: Geometry problem Yes, you will occasionally find errors in your textbooks, but usually this if pretty rare. Errors are more common in earlier editions.

 Tags geometry, problem

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Doc Geometry 5 January 5th, 2015 12:31 AM Ionika Geometry 0 March 2nd, 2014 11:35 AM abctony Geometry 6 May 25th, 2013 01:40 PM Eminem_Recovery Geometry 3 January 15th, 2011 01:28 AM mrhesham Geometry 2 December 7th, 2010 05:11 AM

 Contact - Home - Forums - Cryptocurrency Forum - Top