Homework help?

[@rt]

Hello,
Is there an appropriate place for homework help?
Which is early Maths for engineering (where “help” doesn’t mean cheating or asking for answers).
Cheers

[@rt]

I’ll go ahead since I have NEVER done this, and can show my work.
If any problem, just delete.
Basically, I don’t know why my answer is the same as the question.


Write the equation for a straight line with the following gradient and y intercept:
m=2, c=5.

slope intercept form: y = mx + c
y = 2x + 5.

pick some values for x: -1, 0, 1.
2* -1 + 5 = 3
2 * 0 + 5 = 5
2 * 1 + 5 = 7

plot1: x = -1, y = 3.
plot2: x =  0, y = 5.
plot3: x =  1, y = 7.

draw the graph when you get here.



gradient = rise/run = 2/1 = 2.
y intercept = 5.

y = 2x + 5 … (which is also the question)

[Kremmen]

Well. The slope is the coefficient of x and the intercept at x=0 is the constant part so your answer is the only one fitting the premises.

[Neganur]

Well, if the task was to "Write the equation for a straight line with the following gradient and y intercept[...]"

Then you have answered the problem. I don't see what else is required except drawing the graph, which you also did. What level of education is this?


I'd also not call it a gradient when referring to a line, clearly what they mean is the slope. But that's just me getting caught up in semantics.
(gradient is a vector in that it has both magnitude(=slope) and direction, it points towards the steepest increase)

PS: "slope intercept form: y = mx = c" is a typo yes? You meant to write y = mx + c ?

[Ampera]

1, traditionally, or at least in my experience, Y-intercept is given the variable name b (The generic form is y=mx+b).

2, I would have gotten serious points off for a graph that looked like that. If you can't use graphing paper, write the axis, labeling it and using arrows to express an infinite plane, then put perpendicular ticks for your units. Plot points by placing them in open space instead of making this weird graph like thing that just looks confusing.

Besides that, this is all correct. This is a very basic graphical Algebra problem, to answer a previous question.

[IanB]

Basically, I don’t know why my answer is the same as the question.

As others have said, if you have a straight line with the equation y = mx + b then m is the slope of the line and b is the y-intercept.

What the question is asking you to do is to plot a line with the equation y = 2x + 5 and then verify that the slope (rise/run) is indeed equal to 2, and that the y-intercept (where the line crosses when x = 0) is indeed equal to 5.

The reason the answer is the same as the question is they are asking you to verify what you have been told by doing an experiment. This is crucial to critical thinking: do not simply take what you are told on trust, but rather try to verify for yourself to check that what you are told is accurate.

[madires]

Maybe is just about the visualization. BTW, I'm used to call that a function, i.e. f(x). In a more formal way the y intercept would be written as:
   f(0) = 2 * 0 + 5 = 5
And the slope (first order derivative) would be:
   f'(x) = 2

[Ampera]

Maybe is just about the visualization. BTW, I'm used to call that a function, i.e. f(x). In a more formal way the y intercept would be written as:
   f(0) = 2 * 0 + 5 = 5
And the slope (first order derivative) would be:
   f'(x) = 2

That, however, is far beyond this level of basic Algebra. In the US we don't normally teach functions until much later, never mind derivatives.

[@rt]

Hi,
It’s the end of my first week, but this is jumping ahead to the end of my first quarter.
I think it’s about equivalent High school Maths B (or Maths II in older days).

The question is literally this:
"Write the equation for a straight line with the following gradient and y intercept m=2, c=5”.
How is that asking me to plot the graph?

The plot is my own homework scribble.. this doesn’t get submitted or marked.

Yes, I meant y = mx + c.

[Neganur]

How is that asking me to plot the graph?

"draw the graph when you get here."

[@rt]

No, the question is posted in my post directly above.... all of the rest in my first post is my own work, including where I wrote “draw the graph here”.

[Ampera]

Then they just need the equation you already made. I think the problem is that it's a bit too simple of a question as it's just plugging things in.

[IanB]

The question is literally this:
"Write the equation for a straight line with the following gradient and y intercept m=2, c=5”.
How is that asking me to plot the graph?

It's not. But you made it seem like it was. So:

Question: Write the equation for a straight line with the following gradient and y intercept: m=2, c=5.

Answer: The equation is: y = 2x + 5

That is it. Please explain what you are not sure about?

But is that literally the question? I think the question should have been: "Write the equation for a straight line with a slope of 2 and a y intercept of 5."

When posting questions, be very careful not to paraphrase them or reinterpret them in your own words. Write them exactly as given. Precision is important.

I don't know if you changed the wording of the question here, but if you didn't then the question given to you was a poorly written question.

[@rt]

Ok, back in 2 mins.

[@rt]

I’d post the image except Google have already canned my hosting again.
I did change it a bit to eliminate part b, since I’d only do the same thing again.
The quotes enclose the exact question, and I’m dealing only with part a.

“
5. Write equations for straight lines with the following gradients and y intercepts.

a. m = 2, c = 5
b. m = -1, c = 0.5
“
If it’s as easy as you say it is, isn’t that stupid?

[IanB]

If it’s as easy as you say it is, isn’t that stupid?

Sometimes questions like this are just for revision, to make sure people are following along, and sometimes to set things up for questions that follow.

Also, "easy" is in the eye of the beholder. Some students in 8th or 9th grade may struggle with such concepts.

[@rt]

This is a tertiary preperation course conducted at a University.
I’ve got a year of this for not taking Maths B in high school.
That’s dissapointing, but thanks.

[IanB]

This is a tertiary preperation course conducted at a University.
I’ve got a year of this for not taking Maths B in high school.
That’s dissapointing, but thanks.

You don't have a location shown. May I ask which country you are in?

My sense is that straight lines, slopes and intercepts are usually covered around age 14 or 15 in high school. It seems you might have missed out on a lot of high school math if you are catching up on it now.

[Ampera]

This stuff was technically covered in my College Algebra and Trig course, but only in a cursory form, and we moved onto more advanced stuff, before I swiftly moved onto precalc which was an online course and the greatest waste of my academic time I have ever experienced. Calc 1&2 were really good though, doing stats now as a easy one-off, before moving onto full time education including physics, general sciences, and likely Calc 3.

If you don't know how to do this, and you've just hit uni, I'd say you're in for a bit of a crash course here, as I learned this stuff when I was ~11, maybe 12. (I started my first college course, which was College Algebra and Trig when I just about turned 14, and it was largely review).

[mtdoc]

My oldest son is 11 and in the 6th grade and they have covered this.  Granted, he is in an advanced program, but I think in the US this is something usually covered in 7th or 8th grade (12-14 year olds).

[@rt]

I’m in Australia. The degree I want requires English and Maths B high school pass. I did Physics and some easier Maths subject.

Some of this stuff now is as simple as applying the order of operations and stuff like that. I don’t have any choice but to do it because this will give me the equivalent high school pass for Maths B.

[rstofer]

I’d post the image except Google have already canned my hosting again.
I did change it a bit to eliminate part b, since I’d only do the same thing again.
The quotes enclose the exact question, and I’m dealing only with part a.

“
5. Write equations for straight lines with the following gradients and y intercepts.

a. m = 2, c = 5
b. m = -1, c = 0.5
“
If it’s as easy as you say it is, isn’t that stupid?

Well, the negative slope throws a slight wrinkle in the equation and in the plot.

At least the equations are linear.  That will change and when it does, sketching a graph can become something of a PITA.

Graphing:  www.desmos.com
Calculating: www.symbolab.com

I'm using these every day with my grandson while he works through Calculus I.  It is ALWAYS helpful to have a picture.  And symbolab gives the complete solution, not just the answer.  There are times when a complete solution is educational.

As you get farther along, you will want to use some kind of math program.  Right now, I am fond of MATLAB and wxMaxima.  There are free alternatives to MATLAB but given the reduced price for students, it's a handy thing to have.  Besides, in the world outside academia, math problems aren't solved by hand.

[IanB]

At least the equations are linear.  That will change and when it does, sketching a graph can become something of a PITA.

Graphing:  www.desmos.com
Calculating: www.symbolab.com

I'm using these every day with my grandson while he works through Calculus I.  It is ALWAYS helpful to have a picture.  And symbolab gives the complete solution, not just the answer.  There are times when a complete solution is educational.

As you get farther along, you will want to use some kind of math program.  Right now, I am fond of MATLAB and wxMaxima.  There are free alternatives to MATLAB but given the reduced price for students, it's a handy thing to have.  Besides, in the world outside academia, math problems aren't solved by hand.

Although I recognize the appeal of computer algebra and graphing tools, I am not sure they are good for students.

Students went through their studies for centuries without the aid of such tools. The disadvantage: they had to think a bit harder. The advantage: they became mental athletes with minds that were fitter and better trained than people that did the mental equivalent of riding around in cars and taking the elevator instead of the stairs.

I never had the advantage of graphical calculators or tools like MATLAB when I went through my studies, and I never missed them because they didn't exist yet. Use MATLAB in your professional life by all means, but don't use it while you are learning. Learn how to sketch a graph by hand so you can intuit the shape it is supposed to have. Intuition is a massively valuable tool to have for the practicing engineer.

When you are studying you want to be doing the mental equivalent of going to the gym. Always remember, no pain, no gain.

[@rt]

Nothing I’ve done so far is any more than a line or two of C.
Unfortunately, although I could show understanding of the problems, it needs to be done on paper with non-programmable sci calculator.

Besides, in the world outside academia, math problems aren't solved by hand.

[Ampera]

Personally, I think computerized mathematic tools aren't a bad thing so long as your class doesn't let you get lazy with it.

In my Algebra and Trig class, (which required a TI-83/84 series, but I used an HP-48G moving onto an HP-50G because screw TI and go HP) calculators of course were useful for number tables and basic plots, but as long as it wasn't a CASulator, all I could do was bang out of a few numbers really fast, which definitely helped speed up the learning process. Once Calc 1/2 hit, I upgraded to an HP Prime, and yes, while the 50G is a CASulator, it wasn't something I used in any extent until pre-calc which was just a really shitty online class.

That HP Prime, let me tell you, because of the rules of the class allowing you to use cheat sheets on the test full of whatever examples or generics you want, I could fill that baby up with as many notes as I needed. The CAS functionality REALLY helped me get through the often very thick Algebra that I knew how to do anyways, to quickly check the answers of my problems. Of course there was the possibility of human error, but the HP Prime didn't give you any steps. You either had to give it some, or have everything go in one fell swoop, which only goes so far.

While the other students had TI calculators which cost about as much as my fancy HP Prime (was bought for around 110 USD), I could bang out the answers to entire maths problems in moments. Now, you have to understand in a modern maths class, the answer is 120% worthless. If you only give the answer to a problem, you will be lucky to get 50% on the test. As stated, the HP Prime just lets you check yourself, make sure that you didn't make a stupid mistake on paper. I still had to compute, evaluate, and even graph by hand, using the same tricks and techniques I would use otherwise. It was a GREAT learning tool and assistant, something that I wouldn't have done as well in the class without, not because it helped me cheat, but because it helped me learn.

Today, the HP Prime is the best calculating tool. It even gives PC CAS engines a run for it's money with Xcas being a PC implementation of the same CAS library. However, without RPN, which is the second best feature by a close margin of the HP Prime, seriously RPN is awesome, I always keep an HP Prime emulator on my desktop to use for quick maths.