Question

Find the following by using appropriate property

3/5×(-2/5)+5/2(-3/5)×1/6

Answer 1

Rational numbers:

A number which can be written in the form p /q , where p and q are integers and q ≠ 0 is called a rational number. For example, 5/3 ,−16 /7 are all rational numbers.



Commutative law:

Two rational numbers can be added in any order. We say that addition is commutative for rational numbers. That is, for any two rational numbers a/b and c/d, then, a / b+c/d =c/d+a/b.

Distributivity of Multiplication over Addition . For all rational numbers a, b and c,

a (b + c) = ab + ac

There is a correction in your Question of NCERT
Class 8th Chapter No 1 . Rational Numbers . Page 14 exercise 1.1

(i) -2/3 × 3/5 + 5/2 - 3/5 × 1/6
= -2/3 × 3/5 - 3/5 × 1/6 + 5/2 (by commutativity)
= 3/5(-2/3 - 1/6) + 5/2
= 3/5{(-4 - 1)/6} + 5/2
= 3/5(-5/6) + 5/2 (by distributivity)
= -15/30 + 5/2
= -1/2 + 5/2
= 4/2 = 2