Mark Scheme being picky?

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.

Nice, thanks. It would be so annoying to lose a mark to 'not do what the examiner wants'.

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

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!

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' ?

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....'

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.

I see! Good to know - thank you

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!

One less thing to worry about.

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.