# Rational Numbers

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maths

By: shingh (108 month(s) ago)

By: shingh (108 month(s) ago)

By: rwas (110 month(s) ago)

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### PowerPoint Presentation:

Rational Numbers Maths Assignment Made By : Class - Viii A Aditya Sinha

### PowerPoint Presentation:

The integers which are in the form of p/q where q is not equal to 0 are known as rational numbers. Examples - 5/8; -3/14; 7/-15; -6/-11 Natural numbers – They are counting numbers. Integers - Natural numbers, their negative and 0 form the system of integers. Fractional numbers – the positive integer which are in the form of p/q where q is not equal to 0 are known as fractional numbers. Rational Numbers

### PowerPoint Presentation:

Properties Of Rational Numbers Closure Property Rational numbers are closed under addition. That is, for any two rational numbers a and b, a+b s also a rational number. For Example - 8 + 3 = 11 ( a rational number. ) Rational numbers are closed under subtraction. That is, for any two rational numbers a and b, a – b is also a rational number, For Example - 25 – 11 = 14 ( a rational number. ) Rational numbers are closed under multiplication. That is, for any two rational numbers a and b, a * b is also a rational number. For Example - 4 * 2 = 8 (a rational number. ) Rational numbers are not closed under division. That is, for any rational number a, a/0 is not defined. For Example - 6/0 is not defined.

### PowerPoint Presentation:

Commutative Property Rational numbers can be added in any order. Therefore, addition is commutative for rational numbers. For Example – Subtraction is not commutative for rational numbers . For Example - Since, -7 is unequal to 7 Hence, L.H.S. Is unequal to R.H.S. Therefore, it is proved that subtraction is not commutative for rational numbers. L.H.S. R.H.S. - 3/8 + 1/7 L.C.M. = 56 = -21+8 = -13 1 /7 +(-3/8) L.C.M. = 56 = 8+(-21) = -13 L.H.S. R.H.S. 2/3 – 5/4 L.C.M. = 12 = 8 – 15 = -7 5/4 – 2/3 L.C.M. = 12 = 15 – 8 = 7

### PowerPoint Presentation:

Rational numbers can be multiplied in any order. Therefore, it is said that multiplication is commutative for rational numbers. For Example – Since, L.H.S = R.H.S. Therefore, it is proved that rational numbers can be multiplied in any order. Rational numbers can not be divided in any order.Therefore,division is not commutative for rational numbers. For Example – Since, L.H.S. is not equal to R.H.S. Therefore, it is proved that rational numbers can not be divided in any order. L.H.S. R.H.S. -7/3*6/5 = -42/15 6/5*(7/3) = -42/15 L.H.S. R.H.S. (-5/4) / 3/7 = -5/4*7/3 = -35/12 3/7 / (-5/4) = 3/7*4/-5 = -12/35

### Associative property:

Associative property Addition is associative for rational numbers. That is for any three rational numbers a, b and c, a + (b + c) = (a + b) + c. For Example Since, -9/10 = -9/10 Hence, L.H.S. = R.H.S. Therefore, the property has been proved. Subtraction is not associative for rational numbers. For Example - Since, 19/30 is not equal to 29/30 Hence, L.H.S. is not equal to R.H.S. Therefore, the property has been proved. L.H.S. R.H.S. -2/3+[3/5+(-5/6)] = -2/3+(-7/30) = -27/30 = -9/10 [-2/3+3/5]+(-5/6) =-1/15+(-5/6) =-27/30 =-9/10 -2/3-[-4/5-1/2] = -2/3 + 13/10 =-20 +39 /30 = 19/30 [2/3-(-4/5)]-1/2 = 22/15 – ½ = 44 – 15/30 = 29/30

### PowerPoint Presentation:

Multiplication is associative for rational numbers. That is for any rational numbers a, b and c a* (b*c) = (a*b) * c For Example – Since, -5/21 = -5/21 Hence, L.H.S. = R.H.S Division is not associative for Rational numbers. For Example – Since, Hence, L.H.S. Is Not equal to R.H.S. L.H.S. R.H.S. -2/3* (5/4*2/7) = -2/3 * 10/28 = -2/3 * 5/14 = -10/42 = -5/21 (-2/3*5/4) * 2/7 = -10/12 * 2/7 = -5/6 * 2/7 = -10/42 = -5/21 L.H.S. R.H.S. ½ / (-1/3 / 2/5) = ½ / -5/6 = -6/10 = -3/5 [½ / (-1/2)] / 2/5 = -1 / 2/5 = -5/2 = -5/2

### Distributive Law:

Distributive Law Distributivity of multiplication over addition and subtraction : For all rational numbers a, b and c, a (b+c) = ab + ac a (b-c) = ab – ac For Example – Since, L.H.S. = R.H.S. Hence, distributive law is proved L.H.S. R.H.S. 4 (2+6) = 4 (8) = 32 4*2 + 4*6 = 8 = 24 = 32

### The Role Of Zero (0):

The Role Of Zero (0) Zero is called the identity for the addition of rational numbers. It is the additive identity for integers and whole numbers as well. Therefore, for any rational number a, a+0 = 0+a = a For Example - 2+0 = 0+2 = 2 -5+0 = 0+(-5) = -5 The role of one (1) 1 is the multiplicative identity for rational numbers. Therefore, a*1 = 1*a = a for any rational number a. For Example - 2*1 = 2 1*-10 = -10 