Write the next three rational numbers:

$\frac{-3}{4},\frac{-6}{8},\frac{-9}{12},\frac{-12}{16},.....,.....,.....$

Given pattern is,

$\frac{-3}{4},\frac{-6}{8},\frac{-9}{12},\frac{-12}{16},.....,.....,.....$

The first rational number is $\frac{-3}{4}$.

The second rational number is $\frac{-3\times 2}{4\times 2}=\frac{-6}{8}$.

The third rational number is $\frac{-3\times 3}{4\times 3}=\frac{-9}{12}$.

The fourth rational number is $\frac{-3\times 4}{4\times 4}=\frac{-12}{16}$.

So the next three rational numbers of this pattern are,

$\frac{-3\times 5}{4\times 5}=\frac{-15}{20}$, $\frac{-3\times 6}{4\times 6}=\frac{-18}{24}$ and $\frac{-3\times 7}{4\times 7}=\frac{-21}{28}$

Therefore the next three rational numbers are $\frac{-15}{20},\frac{-18}{24},\frac{-21}{28}$.