Exercise 1B
Q1 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 |
myhelper
Question 1
Answer True (T) or False (F) :
(i) Subtraction is commutative for rational numbers.
(ii) To subtract $\frac{c}{d}$ from $\frac{a}{b}$. We add the additive
inverse of $\frac{a}{b}$ to $\frac{c}{d}$.
(iii) 0 is its own additive inverse.
(iv) The additive inverse of $\frac{-21}{-30}$ is $\frac{-21}{30}$.
(v) While subtracting three or more rational numbers, they can be grouped
in any order.
Sol :
Q2 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 2
Add the following rational numbers :
(i) $\frac{3}{7}$ and $\frac{2}{7}$
(ii) $-\frac{11}{13}$ and $\frac{9}{13}$
(iii) $\frac{-1}{6}$ and $\frac{3}{10}$
(iv) $\frac{-5}{12}$ and $\frac{-7}{18}$
(v) $\frac{6}{15}$ and $\frac{-7}{25}$
(vi) $\frac{13}{14}$ and $\frac{9}{-7}$
(vii) $3 \frac{3}{4}$ and $4 \frac{1}{3}$
(viii) $2 \frac{5}{7}$ and $\frac{-3}{-14}$
Sol :
Q3 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 3
Simplify :
(i) $\frac{5}{6}+\frac{7}{18}+\frac{-11}{12}$
(ii) $\frac{7}{15}+\frac{-9}{25}+\frac{-3}{10}$
(iii) $\frac{-2}{3}+1 \frac{5}{6}+\frac{-3}{2}$
(iv) $4 \frac{1}{5}+\left(-5 \frac{3}{10}\right)+1 \frac{1}{2}$
Sol :
Q4 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 4
Verify the following :
(i) $\frac{3}{4}+\frac{-2}{5}=\frac{-2}{5}+\frac{3}{4}$
(ii) $\frac{-3}{4}+\frac{7}{-8}=\frac{7}{-8}+\frac{-3}{4}$
(iii) $-8+\frac{-11}{-12}=\frac{-11}{-12}+(-8)$
Q5 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 5
Verify that :
(i)
$\left(\frac{-5}{8}+\frac{9}{8}\right)+\frac{13}{8}=\frac{-5}{8}+\left(\frac{9}{8}+\frac{13}{8}\right)$
(ii)
$-20+\left(\frac{3}{-5}+\frac{-7}{-10}\right)=\left(-20+\frac{3}{-5}\right)+\frac{-7}{-10}$
Sol :
Q6 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 6
Find the additive inverse of each of the following :
(i) $\frac{2}{3}$
(ii) 0
(iii) $\frac{17}{9}$
(iv) $\frac{-15}{-11}$
(v) -23
(vi) $\frac{-16}{13}$
(vii) $\frac{8}{-29}$
Sol :
Q7 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 7
Arrange and simplify :
(i) $\frac{1}{2}+\frac{-3}{5}+\frac{3}{2}$
(ii) $\frac{28}{17}+\frac{35}{17}+\frac{-16}{17}+\frac{-23}{17}$
(iii) $\frac{2}{3}+\frac{-3}{5}+\frac{1}{6}+\frac{-8}{15}$
(iv) $\frac{3}{5}+\frac{5}{3}+\frac{-11}{5}+\frac{-2}{3}$
(v) $\frac{4}{3}+\frac{3}{5}+\frac{-2}{3}+\frac{-11}{5}$
(vi)
$\frac{4}{9}+\frac{5}{3}+\frac{-4}{5}+\frac{7}{9}+\frac{-2}{3}+\frac{9}{5}$
Sol :
Q8 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 8
Verify that -(-x)=x, when x= (a) $\frac{7}{6}$
(b) $\frac{-8}{9}$.
Sol :
Q9 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 9
Verify that $-(x+y)=(-x)+(-y)$, when
(a) $x=\frac{3}{4}, y=\frac{6}{7}$
(b) $x=\frac{-3}{4}, y=\frac{-6}{7}$.
Sol :
Q10 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 10
Subtract :
(i) $\frac{1}{5}$ from $\frac{3}{5}$
(ii) $\frac{4}{9}$ from $\frac{-1}{6}$
(iii) $\frac{-4}{15}$ from $\frac{3}{10}$
(iv) $\frac{3}{-4}$ from $\frac{4}{5}$
Sol :
Q11 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 11
The sum of two rational numbers is $\frac{5}{18}$. If one of the numbers
is $\frac{1}{8}$, find the other.
Sol :
Q12 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 12
What number should be subtracted from $\frac{7}{-8}$ to get
$\frac{-13}{12}$ ?
Sol :
Q13 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 13
What should be subtracted from
$\left(\frac{3}{4}+\frac{1}{3}+\frac{2}{5}\right)$ to get $\frac{1}{2}$
?
Sol :
MULTIPLE CHOICE QUESTION (MCQS)
Q14 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 14
What number should be added to $\frac{-5}{16}$ to get $\frac{7}{24}$ ?
(a) $\frac{-29}{48}$
(b) $\frac{15}{48}$
(c) $\frac{29}{48}$
(d) $\frac{21}{28}$
Sol :
Q15 | Ex-1B | Class 8 | SChand Composite Maths | Rational Numbers | Chapter 1 | myhelper
Question 15
$\frac{-5}{7}+\frac{1}{12}+\frac{3}{4}+\frac{-1}{3}+\frac{10}{7}+-\frac{1}{6}$
equals
(a) 0
(b) 1
(c) $1 \frac{1}{21}$
(d) -1
Sol :
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