DIFFERENCE BETWEEN VARIABLE AND CONSTANT

Difference Between Variable and Constant :

In this section, you will learn the difference between a variable and a constant. 

The picture shown below illustrates the difference between a variable and a constant. 

Some Real Life Examples

Constant : 

Let us consider $100 currency. 

What is the value of $100 currency when i have it in Newyork ?

Its value is $100.

What is the value of $100 currency when i have it in Sancfrancisco ?

Its value is $100.

What is the value of $100 currency when i have it in Chicago?

Its value is $100

From the above questions and answers, one thing is very clear. That is,. in whichever part of America i go, the value of the currency $100 is same.  It is not changed in different parts of the country.

So $100 is constant. 

Variable : 

Let us consider a garment whose cost is  x dollars. 

The manufacturer of the garment sells it to the wholesaler at the cost of $40.

So, x  =  $40.

The wholesaler sells it to the retailer at the cost of $44.

So x  =  $44.

The retailer sells it to the customer at the cost of $50. 

So x = $50

Here, the garment is same.

But, when it is in manufacturer, wholesaler and retailer, its cost is different. 

Hence, the cost of the garment x is variable.

Arbitrary Constant

Some English alphabets will have fixed values, but the values will be unknown. 

For  example, let k be arbitrary constant. 

Then, k will have only one fixed value and it is unknown. 

Variables - Practice Problems

Let us look at some problems on simple equations to have better understanding on variables. 

Problem 1 : 

Solve for x :  

x - 2  =  0

Solution :

x - 2  =  0

Add 2 to each side. 

x  =  2

So, the value of x is 2. 

Problem 2 : 

Solve for x :

9x  =  27

Solution : 

9x  =  27

Divide each side by 9.

x  =  3

So, the value of x is 3.

Problem 3 : 

Solve for x :

x + 3  =  -2

Solution :

x + 3  =  -2

Subtract 3 from each side. 

x  =  -5

So, the value of x is -5.

Problem 4 : 

Solve for x :

3x + 6  =  18

Solution :

3x + 6  =  18

Subtract 6 from each side.

3x  =  12

Divide each side by 3.

x  =  4

So, the value of x is 4

In all the above problems, we have got value for the same alphabet x. 

Even though we have the same alphabet x, we don't get the same value for x.

We get different value for x. So the value of x is being changed.

Therefore, x is considered to be variable. 

After having gone through the stuff given above, we hope that the students would have understood the difference between variable and constant. 

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WORD PROBLEMS

HCF and LCM  word problems

Word problems on simple equations 

Word problems on linear equations 

Word problems on quadratic equations

Algebra word problems

Word problems on trains

Area and perimeter word problems

Word problems on direct variation and inverse variation 

Word problems on unit price

Word problems on unit rate 

Word problems on comparing rates

Converting customary units word problems 

Converting metric units word problems

Word problems on simple interest

Word problems on compound interest

Word problems on types of angles 

Complementary and supplementary angles word problems

Double facts word problems

Trigonometry word problems

Percentage word problems 

Profit and loss word problems 

Markup and markdown word problems 

Decimal word problems

Word problems on fractions

Word problems on mixed fractrions

One step equation word problems

Linear inequalities word problems

Ratio and proportion word problems

Time and work word problems

Word problems on sets and venn diagrams

Word problems on ages

Pythagorean theorem word problems

Percent of a number word problems

Word problems on constant speed

Word problems on average speed 

Word problems on sum of the angles of a triangle is 180 degree

OTHER TOPICS 

Profit and loss shortcuts

Percentage shortcuts

Times table shortcuts

Time, speed and distance shortcuts

Ratio and proportion shortcuts

Domain and range of rational functions

Domain and range of rational functions with holes

Graphing rational functions

Graphing rational functions with holes

Converting repeating decimals in to fractions

Decimal representation of rational numbers

Finding square root using long division

L.C.M method to solve time and work problems

Translating the word problems in to algebraic expressions

Remainder when 2 power 256 is divided by 17

Remainder when 17 power 23 is divided by 16

Sum of all three digit numbers divisible by 6

Sum of all three digit numbers divisible by 7

Sum of all three digit numbers divisible by 8

Sum of all three digit numbers formed using 1, 3, 4

Sum of all three four digit numbers formed with non zero digits

Sum of all three four digit numbers formed using 0, 1, 2, 3

Sum of all three four digit numbers formed using 1, 2, 5, 6