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# Variables

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Variable
An unknown quantity which takes various numerical value is called variable.

An unknown quantity can be represented by a variable. Usually, a variable is any letter from the English alphabet that represents an unknown quantity. The relation between the unknown quantity and other quantities can be expressed with the help of the variable. The value of the variable varies with the given condition on the variable.

Constant
A quantity whose value does not vary is called a constant.

Algebraic expression
An expression consisting of variables, constants and mathematical operators is called an algebraic expression.

Mathematical operations such as addition, subtraction, multiplication and division can be easily performed on variables. We can use variables to form expressions based on patterns.

The following are some branches of mathematics:
•  The branch of mathematics where letters are used along with numbers is called algebra.
•  The branch of mathematics that deals with numbers, operations on numbers and properties of numbers is         called arithmetic.
•  The branch of mathematics that deals with the figures and shapes is called geometry.

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### 2 . WHAT IS THE VALUE OF PIE

it is 22/7.. i think you should know this in class 6 :P

### 3 . Mark scored by Shveta are 10 more than twice the marks scored by Reena.

Marks scored by Reena=x. 10+10=20. ( R)=20x Therefore Sheva's marks=20x. 10+2x=29

### 4 . What is algebra

Algebra is the branches of mathematics. It consists of variables and numbers. e.g 2m

### 5 . dear maam , if the question is - show expression , v multipied by -8 then subtracted from 26 ? ans is 26- -8v ? but the variable always comes before ??

26-(-8v)=26+8v
This can also be written as 8v+26.(commutative property of addition)
But I am a boy not a girl.

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