Definition Subset

Sub-set means part of. If we say that America is part of world then America is said to be sub-set of world. So we Define Subsets as the set which is part of another set. For example in library are many book shelves according to the subjects.
Consider a book shelf containing English books. Then the English book shelf will be sub-set of all library shelves.
Consider students in your class which makes a set C and all students in your school which makes a set S. the set C will be sub-set of set S as it is a part of set S or we can say it is contained in set S.  :

Definition Subset / Subsets Definition – sub-sets are those sets whose all elements are contained in some another set.

Let us see properties of sbsets:
Symbol used for sub-set is:  or . Example if A is sub-set of B then we write it as: A B or A B.
A sub-set may be sub-set of more than one set. For example: consider set N = {11, 33, 77}. This set can be sbset of any set containing the elements 11, 33 and 77 like {1, 2, 11, 33, 77}, {a, e, 33, 11, 77} and many more.
All sets are sub-set of themselves. For example set S={English, math, science, GK}. Then the set S contains these elements. We can say that S is sub-set of S.

An empty set (φ) is sub-set of itself and also sub-set of all other sets.
A set is said to be proper sub-set of another set if another set contains the sub-set and also one or more extra elements with it. For example: set A = {c, v, r, e, m} is proper sub-set of B = {c, v, r, e, m ,s} as it contains extra elements s with the elements of A. A set can be proper sub-set of more than one set. For example above set A is also proper sub-set of C ={c, v, r, e, m, d, s, a}. Null set is proper sub-sets of all the existing sets.

If A is sub-set of set B then B is known as super set of B.

A superset can also be sub-set of some other set.

If A is sub-set of B and B is also sub-set of A, then A is equivalent set of B or A=B.

Possible Number Subsets in set A = 2n where n is number of elements in set A.
These are the properties of Subsets Math

Venn Diagram Math

The relationship between two or three sets can be shown diagrammatically in the form of circles called the Venn-diagram. They were first given by the mathematician John Venn and hence the name for the diagrams. As we know set is the collection of unique things which are called the elements of the set. Consider the following Venn Diagram examples, List of odd numbers less than 15 forms a set which can be denoted as set A={1,3,5,7,9,11,13} here each element is unique.

Let us now learn how to draw Venn-diagrams to show the relationship between two sets. Let set A={1,3,5,7,9,11}, a set of odd numbers and set B={1,2,3,5,7,11} set of prime numbers.
The Venn-diagram of these two sets would be as given below,

In the above diagram the two circles represent each set, set A and set B. Both the circles with all the numbers represent ‘Union of sets’.

The green shaded region represents the numbers in both the sets, this is called the ‘Intersection of sets’, the yellow region represents only A, that is the element present in only set A and the orange region represents the element present in only set B.

Thus one glance at the Venn-diagram gives all the possible information which gives a logical relationship between the sets. At times we see Venn diagram lines, these lines are provided to write the elements or at times lines are used to show the relationship between the sets using line shading.

Venn diagram can also be used to show the relationship between three sets which would be a three circle Venn diagram.

For example: In a group of 23 students, 12 read mathematics, 15 read statistics and 11 read Physics, 4 read Mathematics only, 7 read Statistics only, 3 read Physics only, 4 read all the three subjects, 1 reads only Math and Statistics not Physics, 3 read only Mathematics and Physics not Statistics and 3 read only Statistics and Physics not Mathematics. Let us now write down all the given data to draw the 3 circle Venn diagram.

The total number of students is denoted using the symbol ‘µ’ which is ‘mu’, n(MUPUS)= µ=23, Mathematics =n(M), Physics=n(P) and Statistics=n(S). Intersection is shown with a symbol ‘∩ ‘showing the elements common to both the sets.

Elements not present in a set is shown by compliment, not A is A’. n(M)=12, n(P)=11 and n(S)=15. n(M∩P∩S)=4 and hence, n(M∩P)=7, n(P∩S)=7 and n(M∩S)=5. In the Venn-diagram below each color represents a logical relationship,

Least Common Multiple of two Numbers

There are various mathematical concepts and terms that are to be learnt. The term LCM stands for least common multiple. This is an operation and can be carried out on two integers. The answer we obtain is the least common multiple. This denotes the least number that is fully divisible by both the integers.

Now how to find LCM is the question. It is a rather an easy task and can be performed if one is familiar with the basic arithmetic operations of mathematics and number theory. Division is the operation that is most frequently used. So, one must be confident in the division of two numbers.  So, to understand how to find the least common multiple one must be thorough be with the basic concepts in mathematics otherwise it would be really tough to proceed ahead.

So, what is LCM and how can be it found out. The numbers are selected first, for which it has to be found out. Then they are divided by a common number which should be able to divide all the numbers chosen completely. The number which is not divisible by the common number is written as it is for the next step to be performed. In the next again the numbers are divided by a number which is able to divide all the chosen numbers and this continues till ‘1’ is obtained at the end of all the steps of division. The numbers chosen are divided several times till ‘1’ is obtained in the end. Then the product of all the numbers which were used for division is obtained and this gives the least common multiple of the chosen numbers in the beginning.

So, what is the LCM of ‘3’ and ‘2’ is a question that must be answered and can explain the concept better. First a number which divides both ‘2’ and ‘3’ have to be found out. Since there is no common number that divides both ‘2’ and ‘3’ their product is found out. On multiplying ‘2’ and ‘3’, ‘6’ is obtained. So, ‘6’ is the least common multiple of ‘2’ and ‘3’. If two numbers are not divisible by a common number in the beginning itself, then their product itself is the least common multiple of the two. This is apt in the case of two prime numbers. In the example both ‘2’ and ‘3’ are prime numbers.

Multiplying Even and Odd Numbers

Even and odd numbers are two of the most important topics in basic arithmetic. All real numbers can be classified into even numbers and odd numbers. Even number is a number that can be evenly divided into two parts or can be exactly divided by 2. For example: I have to shed almost 12 kg post pregnancy weight . Here, 12 is an even number. On the other hand, odd number is a number that cannot be evenly divided into two parts or cannot be exactly divided by 2. For example: I have already shed 7 kg post pregnancy weight . Here, 7 is an odd number. There are some trend that can be seen while multiplying even and odd numbers. Let’s have a look at the multiplication rules for even and odd numbers in this post.

Multiplying Even Numbers
When two even numbers are multiplied, the result is always an even number. The formula is Even * Even = Even. For example: I need to list 6 different hobbies for kids for 2 magazines. 6 hobbies for kids * 2 magazines = 12. The result is an even number.

When an even number is multiplied by an odd number, the result is always even. The formula is Even * Odd = Even. For example: I have to survey minimum of 10 baby care center across 5 cities. 10 baby care center * 6 cities = 60. The result is an even number

Multiplying Odd Numbers
When two odd numbers are multiplied, the result is always an odd number. The formula is Odd * Odd = Odd. For example: I have to buy 7 play toys for 7 kids. 7 * 7 = 49. The result is an odd number.
When an odd number is multiplied by an even number, the result is always even. The formula is Odd * Even = Even. For example: She has to buy 7 dresses for 4 kids. 7 * 4 = 32. The result is an even number.
These are the multiplication rules for even and odd numbers.

Outer product of vectors in R^3

Outer product of vectors in R^3
Cross product definition:
The outer product is also called the cross product of vectors. The formal definition is as follows:
If vector x = (x1,x2,x3) and vector y = (y1,y2,y3) are vectors in R^3, then their outer product is denoted by x X y and is defined as
x X y = (x1,x2,x3) X (y1,y2,y3)
         = (x2y3 – x3y2, -(x1y3 – x3y1), x1y2 – x2y1) <- cross="" is="" p="" product="" the="" this="" vector.="">Note that the cross product of two vectors is always another vector. Alternatively in matrix notation we can write the cross product identities as follows:
x X y = (|(x2&x3@y2&y3)|, - |(x1&x3@y1&73)|, |(x1&x2@y1&y2)|)

Properties of cross product:
(1) x X y = -y X x
That is because when we do y X x we interchange the rows of the cross product determinants. Interchange of rows results in negative value of the same determinant.

(2) x X x = 0
That is because if a determinant has two identical rows, then the value of the determinant is zero. When finding x X x, the two rows would be identical.

(3) x X ky = kx X y = k(x X y).
Here, k is a scalar. If one of the rows of a determinant has a common factor k, then the k can be taken out of the determinant and the resulting determinant value when multiplied by k gives us the value of the original determinant.

(4) x X (y + z) = x X y + x X z
This is just distributive property. The distributive property is applicable to determinants there for it also applies to the outer product.

Cross product rules:
The following rules apply to all outer products of vectors. The outer product is also called vector product of two vectors.

(1) The vector product of two vectors is always another vector.
(2) The vector product is not commutative as we saw in the first property above.
(3) The vector product is not defined for vectors in R or R^2. It is defined only for vectors in R^3 or higher order dimensions.

Sample problem:
Find the outer product of the vectors x = (1,2,3) and y = (-1,3,5).
Solution:
x X y = (|(2&3@3&5)|, - |(1&3@-1&5)|, |(1&2@-1&3)|) = (10-9, -(5+3), (3+2)) = (1,-8,5) <- answer.="" p="">

Cost Price

Price can be classified into cost price and selling price. Cost price is the value that is paid by someone to purchase goods or products. Cost price is popularly represented as C.P. Selling price on the other hand is the price that a store or product owner sells a product. Selling price is popularly represented as S.P. Below is two examples on cost price and selling price.
• Example 1: Maria bought action toys for 80 rupees per piece and sold it out for 100 rupees per piece. Here, Rs.80 is the cost price of action toys and Rs.100 is the selling price of the same.
• Example 2: Rohit bought building toys collection for Rs.2500 from online. He sold the same collection for Rs. 2000. Here, Rs. 2500 is the cost price and Rs. 2000 is the selling price of the building toys collection.
Cost price can be classified into four main forms – Actual cost, Last cost, Average cost and Net realizable value.
• Actual Cost Price: Actual cost is the complete amount of a product including duty taxes, service taxes and so on. For example: Christy bought role play toys online for Rs.599 exclusive of shipping charges that is Rs.99. Here, actual cost of the role play toys is 599+99 = Rs.698.
• Last Cost Price: Last cost is the value of an item on its last purchase. For example: I bought by mobile phone at Rs.13500 and now the same phone model’s price is Rs. 10000 only. Here, Rs.13500 is the last cost price of the mobile phone.
• Average Cost Price: Average cost is the average of new and old stock values. For example: the new price of a product is Rs. 10 and the old price was Rs.8 and therefore, the average cost is Rs.9.
• Net Realizable Value: Net realizable value is the average price of a product in the market.  For example: The average value of Barbie dolls in market is Rs.199 and it can also be referred as Net realizable value of Barbie dolls.
These are some basics on Cost Price.

Rational expression

A rational expression (in abbreviation as RE) is one of the forms of expressions in algebra. The rational expression definition is an expression which is in fractional form of two expressions. A rational-expression is generally denoted as p/q, q =! 0.. If ‘p’ and ‘q’ are numbers, then it is a fractional number. If ‘p’ is an expression with variable/s and ‘q’ is just a number, then the RE becomes as a simple expression with each coefficients of p is divided by ‘q’.

Rational-expressions have certain constraints which a normal expression may not. As the first one, we said the denominator expression cannot be zero. Thus, a rational expression can have domain and range restrictions. That is, a RE is not defined for the real zeroes of the denominator part. Thus, the domain has to be excluded for such values of the variable/s, and correspondingly the range is affected.

As a convention, the denominators of REs cannot be left with radicals, negative exponents or complex numbers. Putting back them in proper way is called as solving rational expressions. Let us discuss how to solve rational expressions in such cases.

In case of a RE with a radical term in the form (a + sqrt b) in the denominator, multiply both numerator and denominator by the conjugate of (a + sqrt b), which is (a - sqrt b). Now as per the ‘sum and difference product formula’, the denominator becomes as a2 – b, free from radical terms.

In case of complex numbers, the method is exactly same. This process is also called as ‘rationalizing the denominator’.
REs have more prominent place in rational functions. A rational function f(x) is normally expressed in the form f(x) = [g(x)/h(x)]. The domain, range, continuity, asymptotes are all dependent on the nature of g(x) and h(x). A rational function will have vertical asymptotes at the zeroes of h(x). Determining the horizontal asymptotes (HA) of a rational function is a bit lengthy but can me summarized as below. If the degree of g(x) is ‘m’ and that of h(x) is ‘n’, then,

If, (m – n) < 1, then the HA is y = 0, that is, the x-axis.
If, (m – n) = 0, then the HA is y = b, where ‘b’ is the ratio of leading coefficients.
If, (m – n) = 1, then there is no HA but the slant asymptote, is y = mx + b, where ‘mx + b’ is the quotient part of the long division of g(x)/h(x).
If,(m – n) > 1, neither HA or slant asymptote.