Consider the following sets:

[tex]\[ U = \{ \text{points on the coordinate plane} \} \][/tex]
[tex]\[ A = \{ \text{solutions to the equation } y = 2x + 5 \} \][/tex]
[tex]\[ B = \{ \text{points on the line } y = mx \} \][/tex]

For what value of [tex]\( m \)[/tex] does [tex]\( A \cap B = \varnothing \)[/tex]?



Answer :

To find the value of [tex]\( m \)[/tex] such that the sets [tex]\( A \)[/tex] and [tex]\( B \)[/tex], defined as:
- [tex]\( A = \{ \text{solutions to the equation } y = 2x + 5 \} \)[/tex]
- [tex]\( B = \{ \text{points on the line } y = mx \} \)[/tex]

do not intersect (which means [tex]\( A \cap B = \varnothing \)[/tex]), we need to determine when the lines represented by these equations are parallel and non-overlapping.

### Step-by-Step Solution:

1. Equation of Line [tex]\( A \)[/tex]:
The equation described by set [tex]\( A \)[/tex] is:
[tex]\[ y = 2x + 5 \][/tex]

2. Equation of Line [tex]\( B \)[/tex]:
The equation described by set [tex]\( B \)[/tex] is:
[tex]\[ y = mx \][/tex]

3. Condition for Parallel Lines:
For two lines to be parallel, their slopes must be equal. The slope of line [tex]\( A \)[/tex] is 2 (from [tex]\( y = 2x + 5 \)[/tex]).

Therefore, for the lines to be parallel:
[tex]\[ m = 2 \][/tex]

4. Intersection Check:
We now need to check if the lines [tex]\( y = 2x + 5 \)[/tex] and [tex]\( y = 2x \)[/tex], with the same slope, intersect at any point.

Set the equations equal to see if there's a common point:
[tex]\[ 2x + 5 = 2x \][/tex]

5. Solve for [tex]\( x \)[/tex]:
Subtract [tex]\( 2x \)[/tex] from both sides:
[tex]\[ 2x + 5 - 2x = 2x - 2x \][/tex]
[tex]\[ 5 = 0 \][/tex]

This equation is a contradiction, indicating there are no solutions where these lines intersect.

Given that the two lines with the slope [tex]\( m = 2 \)[/tex] are parallel and have no points of intersection, the solution [tex]\( A \cap B = \varnothing \)[/tex] is valid for:
[tex]\[ \boxed{2} \][/tex]