 My Math Forum formula to detect direct or inverse related values
 User Name Remember Me? Password

 Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion

 September 18th, 2016, 07:22 AM #1 Member   Joined: Nov 2012 From: The Netherlands Posts: 40 Thanks: 2 formula to detect direct or inverse related values Hello All via the following x, y values , a formula needs to be decided for the 'Y ' variable. Basicaaly Consider the table below for x and y (are they directly proportional or are they inversely related ? ). and also to find out the corresponding formula. Pl. see the image http://s6.postimg.org/nph5u40dd/math.png I have seemed to find the answer BUT with trial and error for e.g ( 4,11 :--> 4 X 2 = 8 +3) say this is 'Try 1' for ( 12,31 :---> 12 X 2 = 24 +7) and so on also in the (8+3) above , take the '3' & in (24+7) above take the '7' , which gives a pattern of 'multiply with 2' +1 (notice the '1') and when I would repeat the above once again but this time with for e.g ( 4,11 :---> 4 X 3 = 12) say this is 'Try 2' then I just take the (a gamble) of 'Try 1' and 'Try 2' and can settle for 2.5 as the factor so y = 2.5x + 1 is the formula but is there a 'proper' way to get the formula( other than guesswork and unlike the un-structural method like I have done above) ? Thanks in advance September 18th, 2016, 10:02 AM #2 Member   Joined: Nov 2012 From: The Netherlands Posts: 40 Thanks: 2 some more : No this is not a straight line.{ (y = cx ), where c is a constant} neither is this of the format y = c/x or x = c/y i think its an odd one out ( maybe a hyperbola, or an asymptote ...not sure.) all thats given is what I have shown in the picture file. and the instruction is : get the formula...which I have but in a very unstructural manner. can anyone assist on how to crackt his in a structural way ? Thanks, September 18th, 2016, 10:58 AM #3 Math Team   Joined: Jul 2011 From: Texas Posts: 3,034 Thanks: 1621 the data has a constant rate of change ... $\dfrac{\Delta y}{\Delta x} = \dfrac{11-1}{4-0} = \dfrac{5}{2}$ $\dfrac{\Delta y}{\Delta x} = \dfrac{31-11}{12-4} = \dfrac{5}{2}$ $\dfrac{\Delta y}{\Delta x} = \dfrac{71-31}{28-12} = \dfrac{5}{2}$ ... x and y have a direct linear relationship $y = \dfrac{5}{2}x+1$ Thanks from hello_math September 18th, 2016, 11:43 AM #4 Member   Joined: Nov 2012 From: The Netherlands Posts: 40 Thanks: 2 Thanks. Issue is resolved. Tags detect, direct, formula, inverse, related, values Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post hello_math Elementary Math 1 September 18th, 2016 07:24 AM chelsf123 Algebra 5 August 17th, 2013 07:56 AM meghraj Algebra 4 August 8th, 2012 06:50 PM prashantakerkar Algebra 3 November 14th, 2011 11:11 PM karel747 Calculus 1 June 1st, 2008 09:54 AM

 Contact - Home - Forums - Cryptocurrency Forum - Top      