Question

Class 8 - Math H/W ( 14/08/20 Friday)
Ch1:
I.Write additive and multiplicative inverse of the following:
1. - 1/10
2. 3/4
3. -3/13
4. -9/100
5. 500/6
II. Find:
1. 5/7- 2/7
2. 2/15 + 1/2
3. 7/18 - 1/6
4. 14/9 x 2/3
5. 19/9 ÷ 19/180​

Answer 1

1.

(i) Additive inverse of $\frac{-1}{10}$ is (-10).

(ii) Additive inverse of $\frac{3}{4}$ is $\frac{4}{3}$.

(iii) Additive inverse of $\frac{-3}{13}$ is $\frac{-13}{3}$.

(iv) Additive inverse of $\frac{-9}{100}$ is $\frac{-100}{9}$.

(v) Additive inverse of $\frac{500}{6}$ is $\frac{6}{500}$.

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2.

(i)

$\frac{5}{7}-\frac{2}{7} \\ \\ \rightarrow \frac{3}{7}$

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(ii)

$\frac{2}{15}+\frac{1}{2} \\\\\rightarrow \frac{2\times 2 }{15\times 2} +\frac{1\times15 }{2\times 15 } \\ \\ \rightarrow \frac{4}{30} +\frac{15}{30} \\ \\ \rightarrow \frac{19}{30}$

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(iii)

$\frac{7}{18}-\frac{1}{6}\\ \\ \rightarrow \frac{7}{18} -\frac{1\times 3 }{6\times 3 } \\ \\ \rightarrow \frac{7}{18}-\frac{3}{18} \\ \\ \rightarrow \frac{4}{18} \\ \\ \rightarrow \frac{2}{9}$

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(iv)

$\frac{14}{9} \times \frac{2}{3} \\ \\ \rightarrow \frac{28}{27}$

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(v)

$\frac{19}{9} \div \frac{19}{180} \\ \\ \rightarrow \frac{19}{9}\times \frac{180}{19} \\ \\ \rightarrow \frac{3420}{171} \\ \\ \rightarrow 20$

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