Graphing equations.....?

Question

How do u graph these equations? And if u can, can u show me. I'm kind of stuck.

1. -2x+3y= -21
2. 9x+3y= 1
3. 5x-9y= -7
4. 6x-y=4
5. -2x+7y=0
6. 4x+3y=8
7. 12x=2y+1

Answer 1

These are all straight lines (no powers), so all you need to do is to figure out a couple points and connect them.

The easiest cases would be x = 0 and y = 0.

1) -2x+3y= -21

Replacing x with 0:
-2(0) + 3y = -21
3y = -21
y = -7
So one point is (0, -7)

Replacing y with 0:
-2x + 3(0) = -21
-2x = -21
x = 10½
So the other point is (10½, 0)

So go over on the x-axis to 10½. Make a dot.
Go down on the y-axis to -7. Make another dot.
Graph these two points and draw a straight line with a ruler.

The rest should be straight forward. Try one on your own, post the results in the comments and I'll check back to see what you have.

(Here's a hint to #2 --> (0, 1/3) is one point)

Answer 2

Find two points on the line and then draw a line through those 2 points.

First set the X variable = 0 and solve for the Y value. That will give you the first point. Then set Y = 0 and solve for X. That will give you the second point.

For example -2x + 3y = -21

Set x = 0 You get 3y = -21 y = -7 That gives you the first point (0,-7)

Now set y = 0 You get -2x = -21 x = -21/2 That gives you the second point (-21/2, 0)

Plot those points on graph paper and then use a ruler to connect the two points.


This method will not work for number 5, though. In that case pick x=1 solve for y, then pick y =1 and solve for x.

Answer 3

Find two points on the line and then draw a line through those 2 points.

First set the X variable = 0 and solve for the Y value. That will give you the first point. Then set Y = 0 and solve for X. That will give you the second point.

For example -2x + 3y = -21

Set x = 0 You get 3y = -21 y = -7 That gives you the first point (0,-7)

Now set y = 0 You get -2x = -21 x = -21/2 That gives you the second point (-21/2, 0)

Plot those points on graph paper and then use a ruler to connect the two points.


This method will not work for number 5, though. In that case pick x=1 solve for y, then pick y =1 and solve for x.

Answer 4

Change the equation into slope-intercept form (y = mx + b)

so for 1. y=2/3x -7; then y -int = b, and in this case -7, so plot a point at (0,7)...then m = slope which is rise over run, so the slope in this case is 2/3...go up 2 units and over 3 units from the (0,7) which should be (2,10) and then connect the two points