Question

If U= {21, 22, 23, 24, 25, 26, 27, 28, 29, 30} A = {21, 22, 23, 24, 25} and B = {24, 26, 28, 30}, find A – B​

Answer 1

Question

$\begin{array}{c} \tt {U= \{21, 22, 23, 24, 25, 26, 27, 28, 29, 30 \}} \end{array}$

$\begin{array}{c} \tt {A = \{21, 22, 23, 24, 25 \} } \end{array}$

$\begin{array}{c} \tt{B = \{24, 26, 28, 30 \}}\end{array}$

Now, we have to find A - B

Elucidation

The set A - B will include all elements of set A which are not present in Set B.

A = { 21 , 22 , 23 , 24 , 25 }

B = { 24 , 26 , 28 , 30 }

∴ A - B = { 21 , 22 , 23 , 25 }

Note that element 24 isn't the member of set A - B because it is present in set A and B both.

$\underline{\rule{190pt}{2pt}}$

Additional Information

A - B

Elements belongs to Set A but not B

B - A

Elements belongs to Set B but not A

A' = U - A

All Elements in Universal set except those which belongs to set A.

1. A - B' = A - B
2. A' - B = B - A

A∪B

Elements which belongs to either set A or B or both.

A∩B

Elements which belongs to both set A and set B.

Here in question '24' could be treated as its example !!