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If $*$ is a binary operation in a set $A$, then for all $a, b \in A$
1. $a+b \in A$
2. $a-b \in A$
3. $a \times b \in A$
4. $a * b \in A$
If $z=(1,3)$ then $z^{-1}= $
1. $(\displaystyle{\frac{1}{10}},\displaystyle{\frac{3}{10}})$
2. $(-\displaystyle{\frac{1}{10}},\displaystyle{\frac{3}{10}})$
3. $(\displaystyle{\frac{1}{10}},-\displaystyle{\frac{3}{10}})$
4. $(-\displaystyle{\frac{1}{10}},-\displaystyle{\frac{3}{10}})$
$\displaystyle{\frac{3}{2+2i}}=$
1. $1-i$
2. $1+i$
3. $-2i$
4. $\displaystyle{\frac{3-3i}{4}}$
$\overline{z_1+z_2}=$
1. $\overline{z_1}+\overline{z_2}$
2. $\overline{z_1}-\overline{z_2}$
3. $\overline{z_1}+z_2$
4. $z_1+\overline{z_2}$
$|z_1+z_2|$
1. $>|z_1|+|z_2|$
2. $\leq|z_1|+|z_2|$
3. $\leq z_1+z_2$
4. $>z_1+z_2$
If $z_1=2+i$, $z_2=1+3i$, then $z_1-z_2=$
1. $1-7i$
2. $-1+7i$
3. $1-2i$
4. $3+4i$
If $z_1=2+i$, $z_2=1+3i$, then $-i lm (z_1-z_2)=$
1. $2i$
2. $-2i$
3. $2$
4. $3$
Which of the following sets has closure property with respect to multiplication?
1. $\{-1,1\}$
2. $\{-1\}$
3. $\{-1,0\}$
4. $\{0,2\}$
The multiplicative inverse of $2$ is
1. $0$
2. $1$
3. $-2$
4. $\displaystyle{\frac{1}{2}}$

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