Question

Question 12
To get the product 1, we should multiply $\frac{8}{21}$ by

(a) $\frac{8}{21}$

(b) $\frac{-8}{21}$

(c) $\frac{21}{8}$

(d) $\frac{-21}{8}$

Answer 1

We should multiply $\frac{8}{21}$ by $x$.

Then, according to question,

$x\times \frac{8}{21}=1$

$x=\frac{21}{8}$

Hence, we should multiply $\frac{8}{21}$ by $\frac{21}{8}$, for getting the product 1.
Thus, the correct option is (c).