**Constant:-**

Constant is a quantity which has a fixed value.

**For example:-**

4x+5, 5 is the constant.

**Like terms:-**

Terms which have same variables are called like terms

**For example:- **

6pq and 2pq are like terms

**Unlike terms:-**

Terms having different variables are called unlike terms.

**For example:- **

4x and -2y are unlike terms.

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**Perimeter of Square:-**

The perimeter of a square = Sum of all sides = 4 × side

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**For example:- **

Find the perimeter of a square having side length 25 cm.

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**Solution:-**

Perimeter of square = 4 × length of a side = 4a

4 x 25 = 100 cm

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**Perimeter of Rectangle:-**

Perimeter of rectangle = 2(length + breadth)

= 2 (l + b)

**For example:- **

The length and breadth of a rectangular swimming pool are 10 and 8 meters respectively .find the perimeter of the pool.

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**Solution:- **

Perimeter of a rectangle = 2 × (length + breadth)

Perimeter of the pool = 2 × (10 + 8)

= 2 × 18

= 36 meter

**Commutative property of Addition:-**

*a + b = b + a*

For Example:-

2 + 7 = 9

7 + 2 = 9

Thus, 2 + 7= 7 + 2

Result remains the same after interchanging the terms.

**Commutative Property of Multiplication:-**

* a × b = b × a*

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**For Example:-**

6 × 2 = 12

2 × 6 = 12

Thus, 6 × 2 = 2 × 6.

**Distributive Property of Multiplication over Addition:-**

*a × (b + c) = a ×b + a × c*

**For Example:- **

3 x (4 + 5) = 3 x 4 + 3 x 5

3 x 9 = 12 + 15

27 = 27