Posted by Vp on Monday, September 3, 2007 at 1:01pm.
Help: I need an equation for the following problems:
When x=25, y=?
In the function table the values for x are:
x = 3,5,7,9 and y = 8,14,20.26
#2
When x=8, y=?
In the function table the values for x are:
x = 0,2,4,6 and y = 8,18,28,38

MathEquations  drwls, Monday, September 3, 2007 at 1:25pm
In the first case, each increase of 2 in x increases y by 6 (three times as much as the increase in x). To get from x=9 to x=25, x must increasae by 16, so y must increase by 48, from 26 to 74.
#2 can be done the same way, and is even easier. Increase x by 2 and y must increase by 10. You don't need the equation. 
MathEquations  VP, Monday, September 3, 2007 at 1:34pm
Could you break this down, step by step  and the teacher requires and equation for both
Thanks 
MathEquations  Reiny, Monday, September 3, 2007 at 2:00pm
from the first set of data, select two ordered pairs,
e.g. (3,8) and (5,14)
slope =(148)/(53)
= 3
so the equation is y = 3x + b
but (3,8) lies on this so
8=3(3)+b
b=1
and the equation is
y=3x1
so when x=25
y=3(25)1
= 74
do the second one the same way 
MathEquations  VP, Monday, September 3, 2007 at 2:12pm
Thanks so much  I do understand the logic  is there an easier way to set up this equation fro a 5th grader

MathEquations  Kasey, Tuesday, December 9, 2008 at 1:07pm
2x3(x+4)= 5

MathEquations  pertemuel, Tuesday, June 22, 2010 at 9:59pm
(1/3)y2+12=5x