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

Similar questions

Compute the products AB and BA whichever exists the following cases:
$\text{A}=\begin{bmatrix}1&-2\\2&3\end{bmatrix}$ and $\text{B}=\begin{bmatrix}1&2&3\\2&3&1\end{bmatrix}$
To promote making of toilets for women, an organisation tried to generate awarness through (i) house calls, (ii) letters, and (iii) announcements. The cost for each mode per attempt is given below:
  1. ₹ 50
  2. ₹ 20
  3. ₹ 40
The number of attempts made in three villages X, Y and Z are given below:
  (i) (ii) (iii)
X 400 300 100
Y 300 250 75
Z 500 400 150
Find the total cost incurred by the organisation for three villages separately, using matrices.
Write the value of p for which $\vec{\text{a}}=3\hat{\text{i}}+2\hat{\text{j}}+9\hat{\text{k}}$ and $\vec{\text{b}}=\hat{\text{i}}+\text{p}\hat{\text{j}}+3\hat{\text{k}}$ are parallel vectors.
Evaluate the following integrals:
$\int\frac{\text{x}^5+\text{x}^{-2}+2}{\text{x}^2}\text{dx}$
Find the domain of$\sec^{-1}(3\text{x}-1)$
If $\text{A}=\begin{bmatrix}1&1\\1&1\end{bmatrix}$ satisfies $\text{A}^4=\lambda\text{A},$ then write the value of $\lambda.$
Check the points where the constant function f(x) = k is continuous.
Evaluate the following:
$\sin^{-1}(\sin2)$
Write the position vector of the point where the line $\vec{\text{r}}=\vec{\text{a}}+\lambda\vec{\text{b}}$  meets the plane $\vec{\text{r}}.\vec{\text{n}}=0$.
If $\text{x}^\text{m}.\text{y}^\text{n}=(\text{x}+\text{y})^{\text{m}+\text{n}},$ prove that:
$\frac{\text{d}^2\text{y}}{\text{dx}^2}=0.$