CBSE Grade 7 Maths Chapter 9 - Rational Numbers - Subtraction of Rational numbers and its Properties
Operations on Rational Numbers - Subtraction
Additive Inverse
We observe
a + (-a) = 0, where a is a whole number
b +(-b) = 0, where b is an integer
(a/b) + (-a/b) = 0, where a/b is a rational number
a + (-a) = 0, where a is a whole number
b +(-b) = 0, where b is an integer
(a/b) + (-a/b) = 0, where a/b is a rational number
So we say that (-a/b) is the additive inverse of a/b and a/b is the additive inverse for (-a/b)
If we have to subtract two rational numbers then we have to add the additive inverse of the rational number that is being subtracted to the other rational number
a - b = a + (-b)
Perform Subtraction on Rational Numbers with same denominators
In this method
- we will simply subtract the numerator
- the denominator remains the same.
Example
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Perform Subtraction on Rational Numbers with different denominators
In this method
- We will first make the denominators same ( By Cross Multiplication method or LCM Method- explained in the video)
- we will add the additive inverse of the second number to the first number.
Example
