Question

Let A = {1, 2, 3, 4, 5}; B = {4, 5, 6, 7}. Find A – B.

Answer 1

When you take a=1 and b=4
A-B=3
Similarly other will be also 3
So a-b=3

Answer 2

Let A = {1, 2, 3, 4, 5}; B = {4, 5, 6, 7}. Then

A – B=$\left \{ 1,2,3 \right \}$

Step-by-step explanation:

Given A={1, 2, 3, 4, 5}

and B={4, 5, 6, 7}

We have to find A-B i.e A difference B

We know $\textrm{A} -\textrm{B}=\left \{ \textrm{x} | \textrm{x}\in \textrm{A} \textrm{and}\textrm{x}\notin \textrm{B}\right \}$

so $\textrm{A}-\textrm{B}=\left \{ 1,2,3,4,5 \right \}-\left \{ 4,5,6,7 \right \}=\left \{ 1,2,3 \right \}$