After 3 weeks, a corn plant is 2 feet tall. after 9 weeks, the plant is 8 feet tall. write an equation that represents the height y (in feet) of the corn plant after x weeks.

Y=x-1. X repents weeks and 3 minus 1 = 2 and 9 minus 1 = 8.

Seeing weeks is "x" and height of the plant is "y" think of the numbers given as coordinates.
(3,2) & (9,8)

to make an equation, you have to find the slope by:

(y2-y1)      (8-2)      6     1
  =    =  --- = ---
(x2-x1)      (9-3)      6     1

then you use the set up "y=mx+b" where "m" is your slope, and "B" is the height that it already had.

so far it should look like this: y=1x+b
In order to find the "B" you take one of the coordinates and replace the "X" and "Y" with what ever numbers they are.

For instance: (2)=1(3)+b then you solve for "B"

2=3+b
-3 -3

-1 = b
then you replace "B" with what you found and it should now look like this:
y=1x-1 or y=x-1 because x is the same as 1x in a equation.