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    A question asked me to work out the equation of a straight line, after giving me two co-ordinates. I used one of the two equations of a straight line: y=mx+c which I find much simpler, faster and easier to use than y-y_1=m(x-x_1) even though the mark scheme only showed use of the second equation of a straight line. Would I get the same credit for using the first equation?

    Also, for this same question, my final answer was 2y-3x+13=0 but the answer on the mark scheme was 3x-2y-13=0
    If you move all the values from my answer on to the other side of the equals sign, the same answer is obtained. Is my answer equivalent to the answer on the mark scheme, or is it wrong?
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    (Original post by Ishan_2000)
    A question asked me to work out the equation of a straight line, after giving me two co-ordinates. I used one of the two equations of a straight line: y=mx+c which I find much simpler, faster and easier to use than y-y_1=m(x-x_1) even though the mark scheme only showed use of the second equation of a straight line. Would I get the same credit for using the first equation?

    Also, for this same question, my final answer was 2y-3x+13=0 but the answer on the mark scheme was 3x-2y-13=0
    If you move all the values from my answer on to the other side of the equals sign, the same answer is obtained. Is my answer equivalent to the answer on the mark scheme, or is it wrong?
    It's perfectly correct (for both of your questions), you'd get full marks. :yes:
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    (Original post by Zacken)
    It's perfectly correct (for both of your questions), you'd get full marks. :yes:
    Nice, thanks. It would be so annoying to lose a couple marks for 'not doing what the examiner wants'.
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    (Original post by Ishan_2000)
    Nice, thanks. It would be so annoying to lose a mark to 'not do what the examiner wants'.
    Haha, yeah. I agree. Markschemes are quite lenient, really. At least more lenient than you seem to think they are. Which is a good thing.
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    (Original post by Ishan_2000)
    A question asked me to work out the equation of a straight line, after giving me two co-ordinates. I used one of the two equations of a straight line: y=mx+c which I find much simpler, faster and easier to use than y-y_1=m(x-x_1) even though the mark scheme only showed use of the second equation of a straight line. Would I get the same credit for using the first equation?

    Also, for this same question, my final answer was 2y-3x+13=0 but the answer on the mark scheme was 3x-2y-13=0
    If you move all the values from my answer on to the other side of the equals sign, the same answer is obtained. Is my answer equivalent to the answer on the mark scheme, or is it wrong?
    unless it tells you in the question that you should show that the equation of the line is 3x-2y-13=0 then you should put it in that form, if its not specified then it doesn't matter, the examiner knows what you're on about
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    (Original post by Alisahussain1)
    unless it tells you in the question that you should show that the equation of the line is 3x-2y-13=0 then you should put it in that form, if its not specified then it doesn't matter, the examiner knows what you're on about
    Yeah, this question simply told me to put the answer in the form of ax+by+c=0
    This kind of thing has never happened to me, so I was a bit confused when I got a different answer to the mark scheme.

    Thanks anyway.
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    (Original post by Ishan_2000)
    Yeah, this question simply told me to put the answer in the form of ax+by+c=0
    This kind of thing has never happened to me, so I was a bit confused when I got a different answer to the mark scheme.

    Thanks anyway.
    In which case I don't believe you'd of got the full marks then, however if it was just 'state the equation of the line' with no set way they want you to present it then you'd be fine. Just make sure you always re arrange it into the form they want - it would be stupid to lose marks over something so preventable!
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    (Original post by iMacJack)
    In which case I don't believe you'd of got the full marks then, however if it was just 'state the equation of the line' with no set way they want you to present it then you'd be fine. Just make sure you always re arrange it into the form they want - it would be stupid to lose marks over something so preventable!
    But he did put the equation of the line in the required form!

    -3x + 2y + 13 = 0 is in the form ax + by + c = 0.

    Edit to add: in fact, the markscheme will most likely say somewhere in their notes to accept any answer that is \pm k(3x - 2y - 13) = 0. :-)
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    (Original post by Zacken)
    But he did put the equation of the line in the required form!

    -3x + 2y + 13 = 0 is in the form ax + by + c = 0.
    I thought he said he put '2y-3x+13=0' ?
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    (Original post by iMacJack)
    I thought he said he put '2y-3x+13=0' ?
    Yeah, but 2y - 3x + 13 \equiv -3x + 2y + 13, examiners aren't going to quibble over whether the "y term" or the "x term" comes first in your equation.
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    (Original post by Zacken)
    Yeah, but 2y - 3x + 13 \equiv -3x + 2y + 13, examiners aren't going to quibble over whether the "y term" or the "x term" comes first in your equation.
    Yeah they're equal - but I didn't think that was in the same form they were asking for it in. Really? Interesting to know! I was under the assumption they strictly wanted the x term first (hence the 'in the form ax+by....'
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    (Original post by iMacJack)
    Yeah they're equal - but I didn't think that was in the same form they were asking for it in. Really? Interesting to know! I was under the assumption they strictly wanted the x term first (hence the 'in the form ax+by....'
    I think the intention is to just not have it in the y=mx+c form and with integer coefficients
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    (Original post by iMacJack)
    Yeah they're equal - but I didn't think that was in the same form they were asking for it in. Really? Interesting to know! I was under the assumption they strictly wanted the x term first (hence the 'in the form ax+by....'
    No, of course not. They're not going to cut marks off a candidate because he put his x term before his y term. When they say they want it in the form ax+by + c = 0 they basically just mean they want an equation =0 and not something like y = mx + c.

    Here's an excerp from the markscheme, all they require is an equivalent expression with the fact that it is =0 to award the mark.

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    (Original post by Zacken)
    No, of course not. They're not going to cut marks off a candidate because he put his x term before his y term. When they say they want it in the form ax+by + c = 0 they basically just mean they want an equation =0 and not something like y = mx + c.

    Here's an excerp from the markscheme, all they require is an equivalent expression with the fact that it is =0 to award the mark.

    I see! Good to know - thank you
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    (Original post by iMacJack)
    I see! Good to know - thank you
    One less thing to worry about.
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    (Original post by iMacJack)
    In which case I don't believe you'd of got the full marks then, however if it was just 'state the equation of the line' with no set way they want you to present it then you'd be fine. Just make sure you always re arrange it into the form they want - it would be stupid to lose marks over something so preventable!
    Yeah, I just don't think it looks 'nice' (in maths terms) if the answer is an equation that starts with a negative term if there are other positive terms in that equation. That's why, for this particular question, I put the x term in the middle, and began with the y term, but it shouldn't matter which order you put them in, as Zacken said.
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    (Original post by Zacken)
    One less thing to worry about.
    I think it would hurt my eyes too much if I didn't start with a positive co-efficient first anyway
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    (Original post by Ishan_2000)
    Yeah, I just don't think it looks 'nice' (in maths terms) if the answer is an equation that starts with a negative term if there are other positive terms in that equation. That's why, for this particular question, I put the x term in the middle, and began with the y term, but it shouldn't matter which order you put them in, as Zacken said.
    Yeah I get you mate! It's always good to get clarification on these things
 
 
 
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