Problems...

[ringokid]

I have a russian math teacher that does not teach he has had tenor for the last 3 years and can not be fired he just stops getting bonuses here at ohio state universaty... And no im not just whining. the class average is a 42... I need help on his impossible to us take home test.

Any problems would help if anybody can help me with them.

Thanks in advance to anyone.

2) Use newton's method with initial aproximation (a) x0=sqrt(3) (b)x0=1.7320508 (c)x0=1.73205081 to solve the equation x^5-81x=0. Find the exact limits.

3) Find a cubic function g(x)=ax^3+bx^2+cx+d that has a local maximum value of 8 at -6 and a local minimum value of -3 at 7.

4) Sketch the graph of f(x)=(4x^3+9x^2-3)e^(3x). Not using a graphing utility.

5) Sketch the graph of g(x)=(10x^3+5x^2+6x-5)/(x^2+8x-4). Not using a graphing utility

7) Find correct to six decimal places the coordinates of the points on the curve y=cosx that are closest to the point (0,-1).

8) Find the maxima and minima of the function f(x)=(3x-2)sinx+3cosx+1 on the interval [-pi,pi].

9) LEt g(x)=3x^4+x^2-9. a) Find the intervals on which g is increasing or decreasing. (b) find the intervals of concavity and the inflection points.

10) Find the inflection points of the curve y=(x^3-9x^2-30x-41)e^x correct to six decimal places.

11) If g(-1)=3, g(1)=5 and g''(x) greater than or equal to 6, how large can g(0) possibly be>

 

[BigGlenntheHeavy]

\(\displaystyle 3) \ f(x) \ = \ ax^3+bx^2+cx+d\)

\(\displaystyle f(-6) \ = \ 8 \ = \ -216a+36b-6c+d\)

\(\displaystyle f(7) \ = \ -3 \ = \ 343a+49b+7c+d\)

\(\displaystyle f'(x) \ = \ 3ax^2+2bx+c\)

\(\displaystyle f'(-6) \ = \ 0 \ = \ 108a-12b+c\)

\(\displaystyle f'(7) \ = \ 0 \ = \ 147a+14b+c\)

\(\displaystyle Using \ rref, \ we \ get: \ a \ = \ 22/2197,b \ = \ -33/2197, \ c \ = \ -2772/2197, \ and \ d \ = \ 6884/2197\)

\(\displaystyle Ergo, \ f(x) \ = \ \frac{22x^3}{2197}-\frac{33x^2}{2197}-\frac{2772x}{2197}+\frac{6884}{2197}\)

\(\displaystyle See \ graph \ below\)

[attachment=0:2ayxihjm]bbb.jpg[/attachment:2ayxihjm]

 

[ringokid]

thx BigGlenntheHeavy

 

[Deleted member 4993]

I have a russian math teacher that does not teach he has had tenor for the last 3 years and can not be fired he just stops getting bonuses here at ohio state universaty... And no im not just whining. the class average is a 42... I need help on his impossible to us take home test.

Any problems would help if anybody can help me with them.

Thanks in advance to anyone.

2) Use newton's method with initial aproximation (a) x0=sqrt(3) (b)x0=1.7320508 (c)x0=1.73205081 to solve the equation x^5-81x=0. Find the exact limits.

3) Find a cubic function g(x)=ax^3+bx^2+cx+d that has a local maximum value of 8 at -6 and a local minimum value of -3 at 7.

4) Sketch the graph of f(x)=(4x^3+9x^2-3)e^(3x). Not using a graphing utility.

5) Sketch the graph of g(x)=(10x^3+5x^2+6x-5)/(x^2+8x-4). Not using a graphing utility

7) Find correct to six decimal places the coordinates of the points on the curve y=cosx that are closest to the point (0,-1).

8) Find the maxima and minima of the function f(x)=(3x-2)sinx+3cosx+1 on the interval [-pi,pi].

9) LEt g(x)=3x^4+x^2-9. a) Find the intervals on which g is increasing or decreasing. (b) find the intervals of concavity and the inflection points.

10) Find the inflection points of the curve y=(x^3-9x^2-30x-41)e^x correct to six decimal places.

11) If g(-1)=3, g(1)=5 and g''(x) greater than or equal to 6, how large can g(0) possibly be>

This is a Take-home-test !!!!

I hope you'll admit in the front page of the test-answers that somebody-else did the problem #3 & 7 for you - including the graph.

These look like problems from calculus-for-engineers class. Now this guy will get an A in the class - without lifting a pencil.

viewtopic.php?f=3&t=39850&p=154861#p154861 -- no work shown

viewtopic.php?f=3&t=39897&p=154862#p154862 ... no work shown

And we complain about quality of engineers coming into working force....

Teachers should not complain when these pupils turn-up in their classes and cannot do simple graphing analysis.

 

[BigGlenntheHeavy]

\(\displaystyle 8) \ f(x) \ = \ (3x-2)sin(x)+3cos(x)+1, \ -\pi \ \le \ x \ \le \ \pi\)

\(\displaystyle f'(x) \ = \ 3sin(x)+(3x-2)cos(x)-3sin(x) \ = \ 0\)

\(\displaystyle 3xcos(x)-2cos(x) \ = \ 0 \ \implies \ x \ = \ \frac{2}{3}, \ x \ = \ \pm\frac{\pi}{2}\)

\(\displaystyle Hence \ f(-\pi) \ = \ -2\)

\(\displaystyle f(-\pi/2) \ = \ 7.712389\)

\(\displaystyle f(2/3) \ = \ 3.3576618\)

\(\displaystyle f(\pi/2) \ = \ 3.712389\)

\(\displaystyle f(\pi) \ = \ -2\)

\(\displaystyle Hence, \ abs. \ max. \ occurs \ at \ (-\pi/2,7.712389) \ and \ abs. \ min. \ occurs \ at \ (\pm\pi,-2)\)

\(\displaystyle See \ graph\)

[attachment=0:gd89appx]ccc.jpg[/attachment:gd89appx]

 

[ringokid]

I have a russian math teacher that does not teach he has had tenor for the last 3 years and can not be fired he just stops getting bonuses here at ohio state universaty... And no im not just whining. the class average is a 42... I need help on his impossible to us take home test.

Any problems would help if anybody can help me with them.

Thanks in advance to anyone.

2) Use newton's method with initial aproximation (a) x0=sqrt(3) (b)x0=1.7320508 (c)x0=1.73205081 to solve the equation x^5-81x=0. Find the exact limits.

3) Find a cubic function g(x)=ax^3+bx^2+cx+d that has a local maximum value of 8 at -6 and a local minimum value of -3 at 7.

4) Sketch the graph of f(x)=(4x^3+9x^2-3)e^(3x). Not using a graphing utility.

5) Sketch the graph of g(x)=(10x^3+5x^2+6x-5)/(x^2+8x-4). Not using a graphing utility

7) Find correct to six decimal places the coordinates of the points on the curve y=cosx that are closest to the point (0,-1).

8) Find the maxima and minima of the function f(x)=(3x-2)sinx+3cosx+1 on the interval [-pi,pi].

9) LEt g(x)=3x^4+x^2-9. a) Find the intervals on which g is increasing or decreasing. (b) find the intervals of concavity and the inflection points.

10) Find the inflection points of the curve y=(x^3-9x^2-30x-41)e^x correct to six decimal places.

11) If g(-1)=3, g(1)=5 and g''(x) greater than or equal to 6, how large can g(0) possibly be>

This is a Take-home-test !!!!

I hope you'll admit in the front page of the test-answers that somebody-else did the problem #3 & 7 for you - including the graph.

These look like problems from calculus-for-engineers class. Now this guy will get an A in the class - without lifting a pencil.

http://freemathhelp.com/forum/viewtopic ... 61#p154861 -- no work shown

http://freemathhelp.com/forum/viewtopic ... 62#p154862 ... no work shown

And we complain about quality of engineers coming into working force....

Teachers should not complain when these pupils turn-up in their classes and cannot do simple graphing analysis.

Yes it is a take home test and not engineer based math it is calculus level one. This is from a teacher who trys to make students fail i will not get an A in the class if i get an A on this the most i can get is a C. These questions should be in math level 153 and im in 151 and being showed this he does not teach. And if you think i am just coppying i am not i am trying to learn them. This teacher doesnt teach so i am doing the next best thing. And with engineering comes common sense the reason their are people that are shitty engineers who cant do easy work, is because they are stupid and just have photographic memories and get to build bridges. I use logic and common sense. And am majoring in material science. I started my own business in high school but this teacher does not teach i can only do with logic and commen sence what i can learn i cannot figure them out when the book wont teach me nor the teacher.

Sorry for your inconvenience.

 

[Mrspi]

It's gotten seriously depressing to continue to volunteer here.

We used to have just one or two volunteers who cheerfully DID the work for students (even on take-home tests!!!!)

Now it seems to be a matter of gloating for some volunteers to show how smart they are by doing homework AND tests for anyone who asks.

I'd HOPE you're smart if you're volunteering here (though some of what I've seen leads me to question that assumption).

If you have any pride AT ALL as a volunteer, you would NOT give complete answers to someone taking a test. Come on!!! What does that prove???? I, for one, DO worry about the quality of the engineers, physicists, and teachers coming out of college. If someone has handed them answers so that they get their A's, that is CHEATING.

Might be time for me to move on.

 

[Mrspi]

\(\displaystyle 8) \ f(x) \ = \ (3x-2)sin(x)+3cos(x)+1, \ -\pi \ \le \ x \ \le \ \pi\)

\(\displaystyle f'(x) \ = \ 3sin(x)+(3x-2)cos(x)-3sin(x) \ = \ 0\)

\(\displaystyle 3xcos(x)-2cos(x) \ = \ 0 \ \implies \ x \ = \ \frac{2}{3}, \ x \ = \ \pm\frac{\pi}{2}\)

\(\displaystyle Hence \ f(-\pi) \ = \ -2\)

\(\displaystyle f(-\pi/2) \ = \ 7.712389\)

\(\displaystyle f(2/3) \ = \ 3.3576618\)

\(\displaystyle f(\pi/2) \ = \ 3.712389\)

\(\displaystyle f(\pi) \ = \ -2\)

\(\displaystyle Hence, \ abs. \ max. \ occurs \ at \ (-\pi/2,7.712389) \ and \ abs. \ min. \ occurs \ at \ (\pm\pi,-2)\)

\(\displaystyle See \ graph\)

[attachment=0:1ilr40o0]ccc.jpg[/attachment:1ilr40o0]

Yep....YOU can do this.

I'm SO impressed.
I hope that when this student turns in YOUR work on HIS exam, he'll be honest enough to say "someone did this FOR me."

Do you REALLY think you are helping students here??? I'd give some careful examination to my motives if I were you.

 

[Deleted member 4993]

This is a Take-home-test !!!!
Yes it is a take home test and not engineer based math it is calculus level one. This is from a teacher who trys to make students fail i will not get an A in the class if i get an A on this the most i can get is a C. These questions should be in math level 153 and im in 151 and being showed this he does not teach. And if you think i am just coppying i am not i am trying to learn them. This teacher doesnt teach so i am doing the next best thing. And with engineering comes common sense the reason their are people that are shitty engineers who cant do easy work, is because they are stupid and just have photographic memories and get to build bridges. I use logic and common sense. And am majoring in material science. I started my own business in high school but this teacher does not teach i can only do with logic and commen sence what i can learn i cannot figure them out when the book wont teach me nor the teacher.

Sorry for your inconvenience.

Material Science (my major) is a sub-set of engineering.

English is not my first language - I think I had a better english teacher.

 

[BigGlenntheHeavy]

You're kidding, right? There are thousands of websites which explain this, and any student who has been through pre-calculus should be able to explain it as well.

I was merely showing the audience a cute way to solve the problem, sorry, I didn't mean to upset your applecart.

Do you REALLY think you are helping students here??? I'd give some careful examination to my motives if I were you.

Mrspi, you sound like a pedant and remember - ask not who the bells toll for as they might toll for thee.

 

[galactus]

I am not trying to be a smarta**. Really, I am not. May I give some friendly, yet critical, advice?.

Take a look at this:

This is a Take-home-test !!!!
Yes it is a take home test and not engineer based math it is calculus level one. This is from a teacher who trys to make students fail i will not get an A in the class if i get an A on this the most i can get is a C. These questions should be in math level 153 and im in 151 and being showed this he does not teach. And if you think i am just coppying i am not i am trying to learn them. This teacher doesnt teach so i am doing the next best thing. And with engineering comes common sense the reason their are people that are shitty engineers who cant do easy work, is because they are stupid and just have photographic memories and get to build bridges. I use logic and common sense. And am majoring in material science. I started my own business in high school but this teacher does not teach i can only do with logic and commen sence what i can learn i cannot figure them out when the book wont teach me nor the teacher.

Engineers must be able to write as well as know mathematics. Please take care and pay more attention to punctuation, spelling, grammar, etc. When you must write up resumes, draft technical reports, etc. this sort of writing style will not get you very far in the employment area. No, I am not trying to embarrass you or be ignorant. It's just that I see this sort of thing and it makes me wonder where we are headed as a country.
By the way, the teacher has tenure....not tenor. Unless he sings in class and his vocal range is on the high side

Please everyone, lower your hackles. We are here to help and have fun.

Here is some hints on #7:

Use the distance formula, and make the observation that the distance and the square of the distance have their maximum and minimum at the same point. That point being (x,y).

y=cos(x), (0,-1)

\(\displaystyle S=D^{2}=(x-0)^{2}+(y+1)^{2}\)

Remember what y equals and sub it in, differentiate, set to 0 and solve for x.