Question 69260
f(x) = y; make the table look like this:
:
 x | y
-------
-2 |-5
-1 |-2
 0 |+1
+1 |+4
+2 |+7
:
Look at this table and you can tell that it is a linear equation, for each unit
change in x, there is a 3 unit change in y, so really we only need 2 x/y sets
to write a linear equation. Find the slope using the last two coordinates in
the table: x1 = 2; y1 = 4; x2 = 2; y2 = 7
:
Remember the slope (m) equation: m = (y2 - y1)/(x2 - x1) 
:
In our problem: m = (7 - 4)/(2 -1)
m = 3/1 or just +3
:
Use the point slope equation: y - y1 = m(x-x1)
y - 4 = 3(x - 1)
y - 4 = 3x - 3
y = 3x - 3 + 4
y = 3x + 1
Or
f(x) = 3x + 1
:
The graph of this equation looks like this:
{{{ graph( 300, 200, -4, 4, -8, 10, 3x + 1) }}}
:
you can see that all the coordinates in the table are on the graph
Also you can substitute each value for x in the equation and solve for y to
see if it corresponds to the y value in the table.
:
For example when x = -2:   
y = 3(-2) + 1;  
y = -6 + 1; 
y = -5, the given value in the table 
:
Did this help you understand this now? Any questions?