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

Question 40 Exercise 1.1

Q4) Find the multiplicative inverse of the following.

(i) – 13

(ii)\frac{-13}{19}

(iii) \frac{1}{5}

(iv) \frac{-5}{8}\times\ \frac{-3}{7}

(v) -1 \times\frac{-2}{5}

(vi) -1

Solutions 4:

(i): We know that the multiplicative inverse of rational number 'a' is (\frac{1}{a}), such that a \times\frac{1}{a}= 1

Therefore, Multiplicative inverse of -13 is -\frac{1}{13}.

(ii): We know that the multiplicative inverse of rational number 'a' is \frac{1}{a} such thata\ \times\frac{1}{a} = 1

Therefore, Multiplicative inverse of \frac{-13}{19}\ is\ \frac{-19}{13}.

(iii): We know that the multiplicative inverse of rational number 'a' is \frac{1}{a} such that a\times\frac{1}{a} = 1

Therefore, Multiplicative inverse of \frac{1}{5}\ is\ 5

(iv): We know that the multiplicative inverse of rational number 'a' is \frac{1}{a} such that a x \frac{1}{a}= 1

Therefore,

Multiplicative Inverse of\frac{15}{56\ }\ is\ \frac{56}{15}.

(v): We know that the multiplicative inverse of a rational number 'a' is \frac{1}{a} such that a x \frac{1}{a} = 1

Therefore, Multiplicative inverse of \frac{2}{5}\ is\ \frac{5}{2}.

(vi): We know that Multiplicative inverse of 'a' is \frac{1}{a}, such that a x \frac{1}{a}= 1

Therefore, Multiplication inverse of -1 is \frac{1}{-1}

Video transcript
"if a is a rational number then it says if a rational number is multiplied by its multiplicative inputs the product will always be one now to solve this question we will use the same idea now let's see what is their part first the given value of fashion number eight let's see the second button local but it will still have something will be now here we are given rational numbers in form of a product let's see first how to do it it is negative 8 into negative 3 by 7 let's convert it into a proper fraction by multiplying so in numerator it will be negative 5 multiplied by negative 3 divided by 8 multiplied by 7 so we know when we multiply to the negative integers it becomes it into s plus 19 by 56 will be d6 pi right plus equal to bar which means is equal to minus one into minus two by five so one can be minus one by one again one into negative two divided by one this will end up as positive 2 divided by positive 5 would be multiplicative in minus 55 by 2 similarly last part where negative one if in case you want to check any of these you can simply use the given property as 15 by 56 into great thank you "
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