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Question 76204: x-3y=-9 how do you graph this?
Answer by bucky(2189)   (Show Source):
You can put this solution on YOUR website! Given:
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x - 3y = -9
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This is a linear equation in standard form. Probably the easiest way to determine
the graph for this form is by using the following procedure.
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You can draw the graph by first recognizing that when x equals zero the corresponding
answer for y is on the y-axis. Similarly, when y equals zero, the corresponding value of
x is on the x-axis.
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So let's begin by going to the given equation and substituting 0 for x to get:
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0 - 3y = -9
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Solve for y by dividing both sides by -3 to get y = +3. So you now know that the point
(0, +3) is on the graph and this point is on the y-axis.
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Now return to the given equation and substitute 0 for y. When you make that substitution
the equation becomes:
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x - (3*0) = -9
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which you can see leads to x = -9. This gives us the point (-9, 0) which is on the graph
and is a point on the x-axis.
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At this stage you have two points on the graph ... (0, +3) and (-9, 0). Plot these two
points and then use a straight edge to extend a line in both directions through these
two points. This is the graph for this problem. Once you have the graph, it is probably
a good idea to find a point on the graph, and substitute its x and y values into the
original equation to ensure that the equation still balances. This will help to verify that
the graph is correct for the given equation.
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Hope this process makes sense to you and that it helps you to understand graphing
linear equations.
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