Question

How do you graph `-3x+7y=21`?

Answer 1

See below...

Explanation:

Make it into a y= equation first.

so

`-3x+3x+7y =21+3x`

`(7y)/7=(3x+21)/7`

`y=(3x)/7+3`

From this equation, we can see that this line would have a y intersection at 3. So label the point at (0,3)

We also know that the coefficient before the x represents the slope. So slope is 3/7. Slope is also `(rise)/(run)`. (From the points, you rise 3 - since its positive - and run 7 times on the grid - to the right since it’s positive.)

Since we found point (0,3) you can add 3 on the y coordinate, and 7 on the x coordinate to find other points. Then taking those points, you can draw the line to your graph.

Your graph should look something like this