Question 79417
Please explain to me how to sketch the graph of y=5+7x. How do you figure out the numbers in the table when you are constructing a table of values?
:
Usually we write linear equation like this:
y = 7x + 5
:
To construct a table we choose several values for x and solve for y:
From -3 to + 3 is a good start:
:
That table would start out like this:
 x | y
-------
-3 |
-2 |
-1 |
0  |
+1 |
+2 |
+3 |
:
We want to fill in the values for y
:
Our equation (in case you forgot) is y = 7x + 5
Substitute our 1st value, -3 for x and find y
y = 7(-3) + 5
y = -21 + 5
y = -16
:
Now the table looks like this:
 x | y
-------
-3 |-16
-2 |
-1 |
0  |
+1 |
+2 |
+3 |
:
Substitute the 2nd valu, -2 for x and find y
y = 7)-2) + 5
y = -14 + 5
y = -9
:
Now the table looks like this:
 x | y
-------
-3 |-16
-2 |-9
-1 |
0  |
+1 |
+2 |
+3 |
:
Find y for each value of x and your table should look like this:
 x | y
-------
-3 |-16
-2 |-9
-1 |-2
0  |+5
+1 |+12
+2 |+19
+3 |+26
:
On a standard graph with x axis from -6 to +6 and y axis from -16 to +16
plot each value in the table and join the points. It should be a straight
slanted line which looks like this
 {{{ graph( 300, 200, -6, 6, -16, 16, 7x + 5) }}}
:
You have probably noticed that a linear graph like this really only needs 
two points joined by a straight line to include all the rest of the points
I thought it would be good practice to plot several like we did here.
:
Do you comprehend this now?  Any questions?