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

- Math-Equations -
**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.

- Math-Equations -
**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

- Math-Equations -
**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 =(14-8)/(5-3)

= 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=3x-1

so when x=25

y=3(25)-1

= 74

do the second one the same way

- Math-Equations -
**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

- Math-Equations -
**Kasey**, Tuesday, December 9, 2008 at 1:07pm
2x-3(x+4)= -5

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

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