In the [tex]$xy$[/tex]-plane, the slope of the line [tex]$y=mx-4$[/tex] is less than the slope of the line [tex]$y=x-4$[/tex]. Which of the following must be true about [tex]$m$[/tex]?

A. [tex]$m = -1$[/tex]
B. [tex]$m = 1$[/tex]
C. [tex]$m \ \textless \ 1$[/tex]
D. [tex]$m \ \textgreater \ 1$[/tex]



Answer :

To determine the condition under which the slope of the line [tex]\( y = mx - 4 \)[/tex] is less than the slope of the line [tex]\( y = x - 4 \)[/tex], let's analyze the slopes of the given lines.

1. The slope of the line [tex]\( y = mx - 4 \)[/tex] is given directly by the coefficient of [tex]\( x \)[/tex], which is [tex]\( m \)[/tex].
2. The slope of the line [tex]\( y = x - 4 \)[/tex] is given directly by the coefficient of [tex]\( x \)[/tex], which is [tex]\( 1 \)[/tex].

We need to find under what condition the slope [tex]\( m \)[/tex] is less than the slope [tex]\( 1 \)[/tex].

Mathematically, we express this as:
[tex]\[ m < 1 \][/tex]

Thus, the condition that must be true about [tex]\( m \)[/tex] is:
[tex]\[ m < 1 \][/tex]

Considering the given options:
- [tex]\( m = -1 \)[/tex] does not generally apply, as it is a specific value.
- [tex]\( m = 1 \)[/tex] does not satisfy [tex]\( m < 1 \)[/tex].
- [tex]\( m < 1 \)[/tex] correctly reflects the required condition.
- [tex]\( m > 1 \)[/tex] does not satisfy [tex]\( m < 1 \)[/tex].

Therefore, the correct condition is:
[tex]\[ m < 1 \][/tex]

Given the options, the correct one is:
[tex]\[ m < 1 \][/tex]

This corresponds to the third option in the provided choices. The true must-be condition about [tex]\( m \)[/tex]:

[tex]\[ \boxed{m < 1} \][/tex]

In numerical terms, this corresponds to the index [tex]\( 2 \)[/tex] in the list of options. Hence, the numerical result is:

[tex]\[ 2 \][/tex]