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Math Help - help with problem

  1. #1
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    help with problem

    ok I have some problems, its on solving and graphing linear inequalities, the question is 3x-2 < Y. I started by putting it in Y=MX+B form( first thing to do according to notes), which would seem to be Y=-3x + 2, since I am carrying over the numbers to the other side and thus switching the signs. I looked in the back of the book and the graph line has Y intercept at -2 and Slope at up 3 over 1, making it Y=3x-2. I assume that even if I have to flop numbers I do no sign switching as long as Y is already by itself and MX & B is on the other side? Thats the only explanation I can come up with but I don't know.

    Next issue is checking the line and shading one side, I check using point 0, and 0 is not less than -2 so I shade on the right side of the line, but the graph in the back of the book shows the left side being shaded.

    My teacher purposely gives us questions that are in the back of the book so we can self check but I can not figure this out.
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  2. #2
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    Quote Originally Posted by kenny87 View Post
    ok I have some problems, its on solving and graphing linear inequalities, the question is 3x-2 < Y. I started by putting it in Y=MX+B form( first thing to do according to notes), which would seem to be Y=-3x + 2, since I am carrying over the numbers to the other side and thus switching the signs. I looked in the back of the book and the graph line has Y intercept at -2 and Slope at up 3 over 1, making it Y=3x-2. I assume that even if I have to flop numbers I do no sign switching as long as Y is already by itself and MX & B is on the other side? Thats the only explanation I can come up with but I don't know.

    Next issue is checking the line and shading one side, I check using point 0, and 0 is not less than -2 so I shade on the right side of the line, but the graph in the back of the book shows the left side being shaded.

    My teacher purposely gives us questions that are in the back of the book so we can self check but I can not figure this out.
    I don't see how you got y=-3x+2. I You should graph the line y=3x-2

    The innequallity is just y>3x-2. I think you may have been confused because it was written the other way. Just draw the line and shade the region on the left.

    Here's a little tutorial on these kinds of problems:

    Graphing Linear Inequalities
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  3. #3
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    so I am guessing you don't change the signs of the other 2 numbers as long as y is already on one side by itself? I got the negative 3 and positive 2 because I know it should be Y=MX + B, Y was at the end so I thought in order to put it in order I would have to take the two numbers and put them on the other side of the Y which in other situations I have worked meant changing the signs on the numbers.

    Still confused on changing from y < to >, the link says I should flip if multiplying or dividing by negative but I didn't do any of that here, did I?
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  4. #4
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    Quote Originally Posted by kenny87 View Post
    so I am guessing you don't change the signs of the other 2 numbers as long as y is already on one side by itself?
    To learn how to solve literal equations, try an online lesson or two.

    Quote Originally Posted by kenny87 View Post
    Still confused on changing from y < to >, the link says I should flip if multiplying or dividing by negative but I didn't do any of that here, did I?
    To learn how to solve linear inequalities in one variable (which will explain how to handle the inequality sign), try here.

    To learn how to graph linear inequalities in two variables, try here.
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