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NCERT Solutions Class 8 Mathematics Solutions for Exercise 1.1 in Chapter 1 - Rational Numbers

Question 39 Exercise 1.1

Verify that : -(-x) = x for.

(i) x=\frac{11}{15} (ii) x=-\frac{13}{17}

Answer:

\text { (i) } x=\frac{11}{15}

We have, x=\frac{11}{15}

The additive inverse of x is –x (as x+(-x)=0)

Then, the additive inverse of \frac{11}{15} is \frac{-11}{15} \left(\operatorname{as} \frac{11}{15}+\left(\frac{-11}{15}\right)=0\right.

The same equality \frac{11}{15}+\left(\frac{-11}{15}\right)=0 shows that the additive inverse of \frac{-11}{15} \text { is } \frac{11}{15}

\begin{array}{l} \text { Or, }-\left(\frac{-11}{15}\right)=\frac{11}{15} \\ \text { i.e., }-(-x)=x \end{array}

\text { (ii) } x=-\frac{13}{17}

We have, x=-\frac{13}{17}

The additive inverse of x is –x (as x+(-x)=0)

Then, the additive inverse of \frac{-13}{17} \text { is } \frac{13}{17} \quad\left(\right.\text { as }\left(\frac{-13}{17}+\frac{13}{17}\right)=0

The same equality \left(\frac{-13}{17}+\frac{13}{17}\right)=0, \text { shows that the additive inverse of } \frac{13}{17} \text { is } \frac{-13}{17}

\begin{array}{l} \text { Or, }-\left(\frac{13}{17}\right)=\frac{-13}{17} \\ \text { i.e., }-(-x)=x \end{array}

Video transcript
"hello students i am rita your math leader tutor and the today's question is verify that minus minus of x is equal to x for in the first part x is equal to 11 by 15 so we have to verify so first of all we take lhs that is left hand side that is minus minus of x so we can write minus this is our lhs and this one is our and we write here and this one is rhs that is x now we put the values in of x that is 11 by 15 minus minus of 11 by 15 so minus minus become plus 11 by 15 and the value of x is 11 by 15 now lhs is equal to rhs hence very fight hence verified now in the second part we have the value of x is equal to minus 13 by 17 now again we can write lhs and rhs and now we verify it in the lhs we have minus of minus x and in the rhs we have only x so we put the value of x that is minus 13 by 17 and the value of x is minus 13 by 17 now minus minus become plus minus 13 by 17 and here is minus 13 by 17 now the lhs is equal to rhs hence very fight this is hence verified i hope you like this video so please subscribe leto for more updates and do comment your questions thank you "
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