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Thread: Algebra question

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    Senior Member Joanne Vergin's Avatar

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    Exclamation Algebra question

    2x+y=8;y

    What does the semi-colon mean?
    Thanks.
    “Bondservants, be obedient to those who are your masters according to the flesh, with fear and trembling, in sincerity of heart, as to Christ; not with eyeservice, as men-pleasers, but as bondservants of Christ, doing the will of God from the heart” (Eph. 6:5-6).

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    Senior Member Paul DeBaufer's Avatar

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    Re: Algebra question

    Bad proofreading?

    From Wiki:

    Mathematics

    In the argument list of a mathematical function f(x_1, x_2, \dots; a_1, a_2, \dots), a semicolon may be used to separate variables and parameters.

    In differential geometry, a semicolon preceding an index is used to indicate the covariant derivative of a function with respect to the coordinate associated with that index.
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    Senior Member Joanne Vergin's Avatar

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    Re: Algebra question

    So maybe it's 8 or y?
    “Bondservants, be obedient to those who are your masters according to the flesh, with fear and trembling, in sincerity of heart, as to Christ; not with eyeservice, as men-pleasers, but as bondservants of Christ, doing the will of God from the heart” (Eph. 6:5-6).

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    Senior Member Marsha Lynn's Avatar

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    Re: Algebra question

    Quote Originally Posted by Joanne Vergin View Post
    2x+y=8;y

    What does the semi-colon mean?
    Thanks.
    Is this from a text book? It seems there should be an explanation somewhere in the instructions. My best guess would be that you're supposed to solve for y.
    "Pacifism does not mean doing nothing. It means waging peace." - John Watson http://feedly.com/e/s2B2hnZT
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    Senior Member Joanne Vergin's Avatar

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    Re: Algebra question

    Thanks. It's a pre-test that one of my students is taking.
    “Bondservants, be obedient to those who are your masters according to the flesh, with fear and trembling, in sincerity of heart, as to Christ; not with eyeservice, as men-pleasers, but as bondservants of Christ, doing the will of God from the heart” (Eph. 6:5-6).

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    Re: Algebra question

    Quote Originally Posted by Joanne Vergin View Post
    2x+y=8;y

    What does the semi-colon mean?
    Thanks.
    It might help if you could show us the context. Scan the page for us. On the other hand, if this is in a book, there should be an example to follow. It might simply mean "In the equation 2x+y=8 what does y equal?" If this is the case and you are in an "elementary" algebra book, y=-2x+8. This, then, is the formula for a line on a graph. I don't have enough info to help you.
    Thanks Hans Deventer - "thanks" for this post

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    Assistant Site Administrator/Forum Host Jon Twitchell's Avatar

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    Re: Algebra question

    Quote Originally Posted by Marsha Lynn View Post
    Is this from a text book? It seems there should be an explanation somewhere in the instructions. My best guess would be that you're supposed to solve for y.
    This would be my best guess as well.

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    Host Sports forum Shea Zellweger's Avatar

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    Re: Algebra question

    If I saw that in a math text without explanation, I'd solve for Y.

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    Host Book & Movie forums Katelynn Scott's Avatar

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    Re: Algebra question

    it's the secret symbol for STOP DOING ALGEBRA! ;o )
    "I have told you these things, so that in me you may have peace. In this world you will have trouble. But take heart! I have overcome the world." ~ John 16:33

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    Senior Member Steven Burton's Avatar

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    Re: Algebra question

    The answer is 42.
    "Means we use must be as pure as the ends we seek."

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    Senior Member Marsha Lynn's Avatar

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    Re: Algebra question

    Quote Originally Posted by Steven Burton View Post
    The answer is 42.
    Nah, I think that's the answer to some other question. The answer here is 8. The question is, what is the question?
    "Pacifism does not mean doing nothing. It means waging peace." - John Watson http://feedly.com/e/s2B2hnZT
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    Senior Member Steven Burton's Avatar

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    Re: Algebra question

    Well I thought it was the right question/problem, my bad :P.
    "Means we use must be as pure as the ends we seek."

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    Re: Algebra question

    Quote Originally Posted by Steven Burton View Post
    The answer is 42.
    I actually got that answer too when simply copying and pasting the whole thing into my computer calculator. This could be significant in light of this video: "the answer to life, universe and everything" found at

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    Senior Member Eric Frey's Avatar

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    Re: Algebra question

    Quote Originally Posted by Dan Ross View Post
    It might help if you could show us the context. Scan the page for us. On the other hand, if this is in a book, there should be an example to follow. It might simply mean "In the equation 2x+y=8 what does y equal?" If this is the case and you are in an "elementary" algebra book, y=-2x+8. This, then, is the formula for a line on a graph. I don't have enough info to help you.
    Are you sure? I thought y=8-2x

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    Senior Member Charlotte 'Mercer' Burton's Avatar

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    Re: Algebra question

    Quote Originally Posted by Eric Frey View Post
    Are you sure? I thought y=8-2x
    I'm going to have to side with you on this one, Eric.
    "God is still God, and love is still enough." ~Brad Mercer
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    Assistant Site Administrator/Forum Host Jon Twitchell's Avatar

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    Re: Algebra question

    Quote Originally Posted by Eric Frey View Post
    Are you sure? I thought y=8-2x
    Quote Originally Posted by Charlotte 'Mercer' Burton View Post
    I'm going to have to side with you on this one, Eric.
    Except that y=8-2x doesn't give us the same, quickly available information as y=-2x+8.

    From the second format of the equation, I can quickly tell you that the slope of the line is -2, and the intercept is +8. There's a reason why the convention is y=mx+b.
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    Re: Algebra question

    Quote Originally Posted by Eric Frey View Post
    Are you sure? I thought y=8-2x
    At the risk of being labelled "legalistic" and a "fundamentalist" by the "theologians" on board, I have used the commutative property ("The word "commutative" comes from "commute" or "move around", so the Commutative Property is the one that refers to moving stuff around") found at http://www.purplemath.com/modules/numbprop.htm

    John Twitchell is correct. In the form y-mx+b, you can visualize the graph of this line instantly and tell immediately where the line crosses the x axis AND they y axis. You can then draw a straight line between the two points and you have an instant line on a graph. The equation y =-2x+8 then allows you to calculate ANY point on the line. You can then calculate ordered pairs which describe points on the line. Ferinstance, y=0 describes the x axis so if you want to find where this line crosses the x axis, you set y = 0 into this equation so 0=-2x + 8

    The ordered pair describing where the line crosses the x axis is (?, 0). Solving for x in 0 = -2x + 8, we find that x = 4. The line crosses the x axis at (4,0).

    Okay, I'm boring myself too. I'll stop

  18. #18
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    Re: Algebra question

    Quote Originally Posted by Dan Ross View Post
    At the risk of being labelled "legalistic" and a "fundamentalist" by the "theologians" on board, I have used the commutative property ("The word "commutative" comes from "commute" or "move around", so the Commutative Property is the one that refers to moving stuff around") found at http://www.purplemath.com/modules/numbprop.htm

    John Twitchell is correct. In the form y-mx+b, you can visualize the graph of this line instantly and tell immediately where the line crosses the x axis AND they y axis. You can then draw a straight line between the two points and you have an instant line on a graph. The equation y =-2x+8 then allows you to calculate ANY point on the line. You can then calculate ordered pairs which describe points on the line. Ferinstance, y=0 describes the x axis so if you want to find where this line crosses the x axis, you set y = 0 into this equation so 0=-2x + 8

    The ordered pair describing where the line crosses the x axis is (?, 0). Solving for x in 0 = -2x + 8, we find that x = 4. The line crosses the x axis at (4,0).

    Okay, I'm boring myself too. I'll stop
    Sorry, I can't resist. X=0 describes the y axis so to find where the line crosses the y axis set x = 0 in the equation so y = -2(0) + 8. So y = 8. The ordered pair for the point where the line crosses the y axis is (0, ?) or in this case, (0,8)

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    Re: Algebra question

    Now you are going to get some foolish notion that I am obsessive compulsive or some nonsense. Check my work. The original equation is in the form:

    ax + by = c so that a=2, b=1, c=8

    Go to this calculator and plug those numbers in and you will get the answers I gave above:

    http://www.analyzemath.com/Calculato...rceptLine.html

    PLEAS!! Someone stop me! Oops... I have to go change a diaper. ... Later

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