# NCERT Exemplar Solutions Class 8 Mathematics Solutions for Rational Numbers - Exercise in Chapter 1 - Rational Numbers

Question 171 Rational Numbers - Exercise

The numerical expression \frac{3}{8}+(-\frac{5}{7})=(-\frac{19}{56}) shows that _____.

\frac{3}{8}+(-\frac{5}{7})

Take the LCM of the denominators of the given rational numbers.

LCM of 8 and 7 is 56

Express each of the given rational numbers with the above LCM as the common denominator.

Now,

\frac{3}{8}=\frac{3\times7}{8\times7}=\frac{21}{56}

-\frac{5}{7}=\frac{-5\times8}{7\times8}=-\frac{40}{56}

Then,

=\frac{21}{56}+-\frac{40}{56} … [[∵ denominator is same of both the rational numbers]]

=\frac{(21-40)}{56}=-\frac{19}{56}

As the answer is a rational number, we can say that rational numbers are closed under addition.

Related Questions
Exercises

Lido

Courses

Teachers

Book a Demo with us

Syllabus

Maths
CBSE
Maths
ICSE
Science
CBSE

Science
ICSE
English
CBSE
English
ICSE
Coding

Terms & Policies

Selina Question Bank

Maths
Physics
Biology

Allied Question Bank

Chemistry
Connect with us on social media!