Question
For the binary operation multiplication modulo $5 (\times _5)$ defined on the set $S = {1, 2, 3, 4}.$ Write the value of $(3 \times _5 4^{-1})^{−1}$

Answer

The composition table for $\times _5$ on the set $S = {1, 2, 3, 4}$ is
$\times _5​​​​​​​$ $1$ $2$ $3$ $4$
$1$ $1$ $2$ $3$ $4$
$2$ $2$ $4$ $1$ $3$
$3$ $3$ $1$ $4$ $2$
$4$ $4$ $3$ $2$ $1$
Now,
$(3 \times _5 4^{-1})^{-1} = (3 \times _5 4)^{-1} [\because 4^{-1} = 4]$
$= 2^{-1} [3 \times _5 4 = 2]$
$= 3 [\because 2^{-1} = 3]$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free