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# IntMath Newsletter: Interactive ellipses, Wolfram Education Portal

By Murray Bourne, 17 Feb 2012

17 February 2012

1. Interactive ellipse graphs
2. Wolfram's Education Portal
3. Puzzle
4. IntMath Poll: Feelings about math
5. Friday math movies
6. Final thought - moving slowly

## 1. Interactive ellipse graphs New on IntMath.com! Here are some graphs that help you understand basic concepts of ellipses. It doesn't matter if you haven't studied this topic yet - it will still be useful. Go to: Interactive ellipse graphs

## 2. Wolfram's Education Portal

This is a new offering (free for now) from Worlfram, the makers of Mathematica, Wolfram|Alpha and the Demonstrations Project.

They have developed a series of math courses using their new CDF (Computable Document Format) technology, which are basically interactive text books.

Here's the link: Wolfram Education Portal

The courses available at the bottom of that page so far include several algebra topics like:

• Equations and Functions
• Graphs of Equations and Functions
• Graphing Linear Inequalities
• Introduction to Probability
• Solving Systems of Equations and Inequalities
• Exponential Functions
• Quadratic Equations and Functions

Coming soon is calculus, and a math question practice feature.

You'll need to download the (free) CDF player (it's easy and quick) and sign up (also painless). In tiny font, it says:

"Wolfram Education Portal is now is avaliable for free, but it might be paid after the official release."

Certainly worth checking out while it's free! Wolfram Education Portal

## 3. Puzzle

I had many requests to bring back the puzzle feature. So here we go.

Question: The Egyptians used only unit fractions (that is, the numerator was 1). So they would write 3/5 as 1/2 + 1/10. How would they write 11/13?

You can only use addition (not minus) and use as few fractions as possible. You can submit your answer here.

## 4. IntMath poll: Feelings about Math

The recent IntMath Poll asked readers how they feel about math. Here are the results.

The best way to describe how I feel about math is:

I enjoy math
41%

It’s OK but I find it hard
30%

I hate math
24%

No strong opinion
4%

It's sad that 1/4 of the respondents answered with a negative view about math. Hopefully IntMath has helped some of them to like it some more!

Current poll: The current poll asks if you think the math you are studying will be useful for your future job.

You can answer on any page in IntMath.com

## 5. Friday math movies (a) Ken Robinson animated How can we fix education? This is a clever animation of Ken Robinson's ideas, talking about why education often doesn't work as intended. Friday math movie: Ken Robinson animated (b) How it feels to have a stroke Here's a story about a brain scientist who had a massive stroke at age 37 - and who lived to tell the fascinating tale. Friday math movie: How it feels to have a stroke

## 6. Final thought: moving slowly

For many students, math class goes very slowly. Here's a Chinese saying that's worth thinking about.

Don't worry about moving slowly, worry about standing still. [Chinese proverb]

Until next time, enjoy whatever you learn.

See the 25 Comments below.

### 25 Comments on “IntMath Newsletter: Interactive ellipses, Wolfram Education Portal”

1. Dineth says:

1/13 + 1/13 + ......thirteen times.

2. don miller says:

used one loop
100: n=n+1
test =1/n
sum =sum +test
if sum < 11/13 then 100
sum=sum-test
goto 100

11/13 = (1/2) + (1/3) + (1/78)

good problem

3. guido verbraeken says:

11/13 = 33/39 = 13/39 + 13/39 + 7/39
= 1/3 + 1/3 + 3/39 + 3/39 + 1/39
= 1/3 + 1/3 + 1/13 + 1/13 + 1/39

1/13+10/13=11/13

5. CHARLES TEMBO says:

1/13+1/65+1/65

6. Wendy says:

1/2+1/4+1/13+1/52

7. Tomas Garza says:

11/13 = 1/2 + 1/3 + 1/78

8. Sachin Sapkal says:

(1/4) + (1/(52)) + (1/(13)) + (1/2)

9. Laureli Sluggett says:

1/3 + 1/2 + 1/78 = 11/13

10. Greg says:

1/2 + 1/3 + 1/78 .

11. ARUN KUMAR A says:

1/2+1/3+1/78 = 11/13

12. Karen Remington says:

My answer to puzzle 11/13= 1/78 + 1/12 + 1/4 + 1/2

13. dilli prasad sapkota says:

thank you sir to this informative article.I absolutely benefited from this article.

14. Francis Kisner says:

It seemed to me that starting with an even denominator would help so I expressed the fraction in different forms. For each, I removed the 1/2 and looked at the remainder. If it was broken so that one piece was a unit fraction, what would be left over? Repeating the exercise a few times led to 11/13 = 1/2 + 1/3 + 1/78

11/13 =
22/26 = 13/26 + 9/26 = 1/2 + 1/26 + 8/26 = 1/2 + 1/26 + 4/13
33/39 =
44/52 = 26/52 + 18/52 = 1/2 + 9/26 =
55/65
66/78 = 39/78 + 27/78 = 1/2 + 26/78 + 1/78 = 1/2 + 1/3 + 1/78
39/78 + 26/78 + 1/78 = 66/78 = 11/13

15. Murray says:

Thanks everyone for your replies on the Eqyptian fraction problem.

You can see why mathematicians worked hard to come up with a better numeration system. I'm glad we have the base 10 system!

16. Brew Mowl says:

11/13 = 6/13 + 5/13

Thanks very much for this unit fraction and hope to get more from you.

17. George Walters says:

1/2 + 1/4 + 1/8 + 1/26

18. George Walters says:

Fun problem. Sent it to my grandson who has taken fractions.

19. SIVY FARHI says:

It is easy; 11/13 = 1/2 + 1/3 + 1/78
First take the hihest unit fraction an subtract it from 11/13.
Then take the next highest unit fraction, which is 1/3 and subtract it from 11/13 - 1/2.

22/26 - 13/26 = 9/26 note 9/26 > 1/3

27/78 - 1/3 = 27/78 - 26/78 = 1/78

20. George Walters says:

Geez I can't do arithmethic any more. the answer I get is
1/2 + 1/3 + 1/78

21. John says:

1/2 + 1/4 +1/13 + 1/52 = 44/52 = 11/13

22. Rina Sengupta says:

1/2+1/4+1/13+1/52 = 44/52 = 11/13

23. Wynill says:

1/2+1/4+1/8+1/28=11/13

24. nkupiarity says:

11/13=1/2+9/29..ans

sol: 1/2+9/26=(13+9)/26
=22/26
=11/13. ans

25. Saran says:

1/2 + 1/3 + 1/78.. dats it..

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