Question

Express $\frac{4}{7}$ as a rational number with denominator
(i) 21
(ii) −35

Answer 1

(i) Denominator of $\frac{4}{7}$ is 7.
7 should be multiplied by 3 to get 21.
Multiplying both the numerator and the denominator by 3:

$\frac{4\times 3}{7\times 3}$= $\frac{12}{21}$

$\frac{4\times 3}{7\times 3}$= $\frac{4}{7}$

(ii)
Denominator of $\frac{4}{7}$ is 7.
7 should be multiplied by -5 to get −35.
Multiplying both the numerator and the denominator by −5:

$\begin{array}{l}\frac{4\times (-5)}{7\times (-5)}=\frac{-20}{-35}\\ \frac{4}{7}=\frac{-20}{-35}\end{array}$