Question 107395
The method to use in solving this problem is to rearrange the given equation into the point-slope 
form. The point-slope form of a linear equation is:
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y = mx + b
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m, the multiplier of x, is the slope of the graph, and b, the constant is the value on
the y-axis where the graph crosses the y-axis.
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You were given the equation:
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3x + y = -2
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You want to get y by itself on the left side of the equation. You can do that by getting rid
of the 3x on the left side. You can do that by subtracting 3x from both sides of the equation.
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When you subtract 3x from the left side, it combines with the 3x that was given, and the
two cancel out. Therefore, the 3x disappears from the left side. And when you subtract 3x 
from the right side, -3x appears on the right side.  So by subtracting 3x from both sides
the equation becomes:
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y = -3x -2
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Compare this equation to the point-slope form of y = mx + b. When you do, you see that
the left side is y. And on the right side, m (the multiplier of x) compares to -3 in your
problem. Since m is the slope of the equation in point-slope form, then you can immediately
say that the slope in your problem is -3. Notice also that b (the constant) compares to
-2 in your problem. And since b is the intercept on the y-axis, you can say that in your
problem the y-intercept (that is, the value on the y-axis where the graph crosses the
y-axis) is - 2. 
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In summary, the graph of the given equation is a straight line. It intercepts the y-axis
at y = -2 and it has a slope of -3 ... meaning that for every 1 unit you move horizontally
from a point on the graph, the graph then goes down 3 units. [The down direction is because
of the minus sign on -3.]
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The graph of y = -3x - 2 looks like this:
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{{{graph(600,600,-10,10,-20,20,-3x-2)}}}
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Hope this helps you to understand this problem and helps you to find where you went astray.
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