## 5.09.2015

### The problem about the garden area

 The problem about the garden area

Why such a strange image to task about the area of ​​the garden? Because the problem itself, to put it mildly, very strange. Here's how it sounds:

The garden occupies 80 hectares. Apple trees occupy 5/8 of the area, and 31% of cherry trees. How many hectares of area under apple trees larger than the area under the cherry trees?

Let's first solve this problem for those students who want to write off the stupid decision, and only then talk about the strangeness of this problem.

The first action we define the area that is occupied by apple trees in the garden. To do this, the total area of ​​the garden should be multiplied by the fractional expression of the area under apple trees.

80 * 5/8 = 50 ha

The second area of ​​action is determined that the garden occupied cherry trees. Take the common garden area, multiplied by the number of cherry trees per cent and 100 per cent share. Interest on interest reduced and as a result we get an area of ​​hectares.

80 * 31%: 100% = 24.8 ha

The area under apple trees we really get more than the area under the cherry trees. Takes away from smaller and larger area of ​​the results.

50 - 24.8 = 25.2 ha

Answer: The area under apple trees on 25.2 hectares more than the area under the cherry trees.

Without checking any decision can be considered incorrect. How to check the solution to this problem? It is necessary to put together the area under apple trees and the area under the cherry trees. This result should be compared with the total area of ​​the garden. If the sum is greater than the total area, so we decided not to challenge properly. If the sum is equal to or less than the total area, so our decision is correct.

50 + 24.8 = 74.8 hectares of less than 80 hectares

In most curious students immediately arises a natural question: what else is growing in this delicious daze, about what we were afraid to tell?

It was a children's nursery problem solution. Now the conversation for adults. This is the task of the textbook, which approved the Ministry of Education as an educational tool. The condition of this problem and at the same time used the percentage of fractional parts of a whole. Normal literate people'd never allow it. They used a ratio or percentage. Only an idiot is able to dump everything into one pile. The author of this task is illiterate idiot who either do not understand what he was doing, or for approval of a textbook command is ready to do anything. Stati, the quality of textbooks is very well characterizes the quality of all education. Our education is built on the principle of "one fools compose tutorials, others say they are fools".

For example, I'll write down the number on the same principle that is used by the author about the problem area of ​​the garden. I simultaneously use two forms of records: number and letter. That's what I got:

2 thousand three hundred 45

As you can see, only idiots can do so. Competent people will write down this number as follows:

2345 or two thousand three hundred forty-five

Why am I so vehemently opposed to such problems? Children - they are like a sponge that absorbs everything. If it is written in the book, then you can do so. As a result, we get the next portion of the idiots who write stupid textbooks that stupid leadership approves a flock of idiots. Just because they are so used to be taught.

What would you say there is not mathematics, but knowledge of mathematics lies not in the ability to accurately repeat all the things the teacher taught. Knowledge of mathematics - is the ability to competently and simply express their thoughts in the language of mathematics.

## 5.06.2015

### The six faces of a parallelepiped

Here is such a question: "Parallelepiped. Explain where he has six faces?". If mathematics is not able to clearly explain to you the parallelepiped design, then I'll try to do it. Will speak only about the faces of the parallelepiped, without delving into other structural details of the mathematical model, we are not in the showroom, and I'm not a manager trying to sell you an outdated model of the parallelepiped.

So, imagine that you, as if nothing had happened, went to sleep in his rectangular (this clarification is important) room. And at night you wake up in the current model of the box in full size! No need to panic. Easy start counting the brink of mathematical miracle. The wall with the window - this is the first bound. The wall opposite the window - this is the second face. The walls of the left and right of the window - this is the third and fourth edges. The floor - this is the fifth face. Ceiling - this is the sixth and final face. Great mathematical revelation: the number of faces does not depend on the order of their conversion, the main thing - do not miss it.

If you are up to this point has not yet fallen asleep, the next question is what to do next? Mentally, we develop a mathematical papyrus entitled "Set Theory", looking for the head of "Infinite math scores sheep" and start counting. People say this is very good mathematical procedure helps insomnia.

Just I want to honestly admit that I have lied a little. Not a rectangular room is a working model of a rectangular parallelepiped, but quite the contrary - a cuboid is a mathematical model of the room. This is particularly evident during the repair. The area of ​​the walls will be the surface area of ​​the side faces of the cuboid. The area of ​​floor or ceiling is determined as well as in the area of ​​the base of the box. Of course, the builders made their nuances in the rules for determining the areas of math, but we will not specify now.

Incidentally, the rectangular room is entirely dependent on the quality of construction. It is only in ancient Greece mathematics was so developed that famous building of the Parthenon in Athens was built with almost no right angles and straight lines. There's a base architecture of the building was laid not a mathematical perfection, and optical illusions. I'm afraid of modern mathematics such a task is not on the shoulder - too high in the clouds, they soar. But we digress from faces of a parallelepiped.

If you count the face of the parallelepiped you wanted during the day and not at night, then pull out from the wardrobe of a rectangular box with shoes. The bottom of the box - it is one face, it is also the lower base of the box. The lid of the box - a second side, she's upper base. The four walls of a shoebox - it faces the third to sixth.

We have considered six faces of a rectangular parallelepiped. If angles are not straight and curves? In this case we are dealing with a conventional parallelepiped, not rectangular. On the number of faces is not affected. Well, think, a little crushed a parallelepiped. By the way, mathematics bend rectangular parallelepipeds or align usual? I'm on the algebra of interesting to see. However, the mathematician's simple: uttered the sacred mantra "Let there be given a parallelepiped" and that he had gleaming white chalk on a blackboard. Life is complicated. There are many ways to straighten the curvature and parallelepipeds - by a heavy sledgehammer, to flirty "Oh, please!". About algebra of these methods can not even ask.

Seriously speaking, the algebra and rectangular, and the usual parallelepipeds is exactly the same. Bends and leveled a parallelepiped using sines of the angles between the ribs. In all corners of the rectangular parallelepipeds straight sinuses and their unity. Lazy math just does not write these sinuses in formulas. In conventional Parallelepipeds sines of the angles is less than one, so willy-nilly have to mathematicians in their formulas to write.

In conclusion, as they say teachers, fix the passed material. As a fixative use a simple children's coloring book, which paint the six faces of a parallelepiped.

 The six faces of a parallelepiped

I recall that the parallelepiped, unlike the quadrangular prism opposing faces are parallel, and the base is a quadrilateral with parallel sides: square, rectangle, diamond or parallelogram. However, mathematicians believe that a parallelepiped is a kind of prism. So they have written in the definition. With the same success it can be argued that the prism is a kind of parallelepiped. Simply rewrite the definition, as a textbook on mathematics - it is not the Bible.

## 4.27.2015

### Increased - that's a plus or multiply?

If you have a question: "Increased - is that a plus or multiply?", then definitely no answer to it. You need to read or listen to what's next. If "increased by as much as something something", then this addition and the plus sign. For example, the number 7 is increased by 2 units. What are we doing? To previous value we added increase and get new value:

7 + 2 = 9

 Increased

If "increased in so many times," it is multiplication. For example, the number 7 is increased in 2 times. It is necessary to multiply the previous value of the specified number of times, and we get a new meaning:

7 * 2 = 14

As you can see, the numbers in the above examples are the same, and the result is different. It all depends on how to formulate a thought.

## 4.21.2015

### Snail on a pole

Objective: Snail crawling on a pole height of 10 meters. During the day, she rises to 4 meters per night descends to 3 meters. For some time the snail reaches the top of the column?

 Snail on a pole

To solve this problem about a snail on a post need to revise some of its condition. The day the snail takes off the pole to a height of 4 meters. The post has a height of 10 meters. Reformulate the question: at what height should be a snail to a running start to fly to the top of the column? The answer to this question is easy to calculate:

10 - 4 = 6 meters

Now the second question: how many days should snail fidgeting up and down the pole to reach a height of 6 meters. Again, take the hands of the math and think:

6 / (4 - 3) = 6 days

As a result, we have six days cochlea will need to enter the starting position for a breakthrough victory, and one day for the race victory. The result is that the triumph of a snail on a post we will see after 7 days.

The same mathematical problem can be formulated with a modern twist. Look how it will sound in the Russian mathematical textbooks soon: From the border to Russia at the borders of NATO distance of 10 thousand kilometers. Green men move per day from the Russian border to NATO at the border at a distance of 4000 kilometers. During the night, NATO troops cast of unknown green men on the 3,000 kilometers back to Russia. How many days disappear NATO? The answer to this problem is the same: after 7 days of the great light of the Russian world illuminate the whole of Europe. By the way, the light of the Christian faith had once lit up Europe funeral pyres of the Inquisition. And the Third Reich sprawling across Europe recently. We must not forget history.

## 4.20.2015

### 9 multiply 7 equals

Immediately write a ready answer: 9 multiply 7 equals 63. So we have the multiplication table says that we all have been taught, but to the end, many of us have not learned. I'm not an exception. Natural laziness and chronic multiple sclerosis did not allow me to remember this vital piece of mathematics. But it is knowledge of mathematics allows me to easily cope with this column multiplication tables. I just calculate the result I needed.

We all know that when multiplied by a permutation of the factors does not change the result. If somewhere sometime mathematics will tell you otherwise, do not believe them - they are wrong. Simple math multiplication like to call it, that in fact is not a multiplication. For example, if we call a cow "Multiplication", it then becomes to turn milk and poop in the hay. After all, the cow to the mathematical action has nothing to do.

So, I always use the following equation:

9*7 = 7*9

Next is quite simple. That number, which must be multiplied by 9, I multiply by 10 and take away his once:

7*9 = 7*10-7 = 70-7 = 63

Multiplied by 10 is very simple - have added to the number of the toe and the result is ready. Subtract this number from a small number of possible even without a calculator. Now you can easily cope with any stitch multiplication table 9.

For example, if we need to multiply 9 by 9, proceed as follows:

9*9 = 90-9 = 81

If needed multiply 9 by 3:

9*3 = 3*9 = 30-3 = 27

In all these transformations have no miracles, we just use the normal math.

 9 multiply

My personal opinion is: better to use the thinking abilities of their brain than clog the brain remembering any nonsense. Even if this nonsense forced to learn mathematics.

### Stupid triangle top view

Maybe it's someone not very pleasant, but stupid triangles does not happen, there are only stupid people. But wits on the Internet are often looking for a stupid triangle, top view which they would very much like to see. Show.

 Stupid triangle top view

First, let's talk about the name of this type of triangles. Call similar triangles stupid - a sign of illiteracy. As they say now, "politically correct" will call such triangles "obtuse". All the triangles which have one angle greater than 90 degrees, are obtuse triangle. It's not a shame, is not a defect, just that physique is obtuse triangles. However, each obtuse triangle always has a couple of sharp corners. So, just in case.

Now let's talk about the kinds. No triangles on the kinds and types of top side of the window. Obtuse triangle top looks exactly the same as the bottom. But the side view is not pleasing to the eye - is just a regular interval. From the window you are unlikely to consider anything, but in a notebook at a neighbor's party this triangle you can see from many angles. In this case the obtuse triangle will look quite different, what it looks like from above. Describe such a wonderful transformation is possible by means of projective geometry, descriptive geometry, trigonometry, or poems. Who like more.

## 4.08.2015

### How not to change the signs inside the brackets?

All of us are taught to change signs when opening or closing brackets of the expression in brackets, if before the brackets minus sign. Let's look at this tedious process for half-dead examples.

11-(2+5-4) = 11-3 = 8

Before the expression in brackets is a minus sign, it means that the disclosure of the brackets need to change all the signs to the contrary all the numbers that are inside the parentheses. Consider the same example, but without the brackets.

11-(2+5-4) = 11-2-5+4 = 9-5+4 = 4+4 = 8

Now let's try to take a part of the expression in parentheses.

1+2+3+4 = 10

Naturally, you ask: "Where is the minus sign?!" Do not worry, now appear.

1+2-(-3-4) = 3-(-7) = 3+7 = 10

I put in front of the brackets and the minus sign to change the sign before the numbers inside the parentheses. In disclosing the brackets again I changed the sign, because before my braces a minus sign. In the end, the result remained unchanged.

Now a more complex example.

17-6+9 = 20
17-(6-9) = 17-(-3) = 17+3 = 20

As you can see, continuous headache turns out, when suddenly appears before the brackets the minus sign. How not to change the signs inside the brackets? Very simply - no need to put a minus in front of the brackets. Look how it's done.

17-6+9 = 17+(-6+9) = 17+(3) = 17+3 = 20

Now consider the last two examples under the microscope. In the first case I put the first parenthesis after the minus sign. I like a knife cut a negative number into two parts - a minus sign and a positive number. The minus sign was in front of the bracket, and a positive number - within the brackets. Look.

17-(6........

In fact, we are in parentheses conclude a positive number, which until then was negative. Changing the sign of the first number in parentheses passed on complete autopilot without our intervention. A sort of a machine circumcision minus sign in numbers. But with the other numbers that fall into these brackets are already having problems. Signs they need to be changed manually.

In the second case I put the opening bracket before the minus sign. In fact, I put in brackets a negative number with a minus sign. Here's how it looks initially.

17(-6.........

Now, between numbers 17 and bracket there is no sign that mathematics implies multiplication. But I do not have anything to multiply. To answer in the solution remained the same example, I set the bracket additional "plus" sign.

17+(-6.........

Now everything is correctly written. Before the parentheses appears the plus sign and signs before the numbers inside the brackets intact. No mathematical crime I did not commit, just competently get rid of extra action on the replacement characters inside the brackets. Why mathematics always do? They had not taught this. If it is not in the curriculum, and then teach you that no one will. Math enough to know, you need to also know how to use her.