25. In the standard [tex]$(x, y)$[/tex] coordinate plane, what is the slope of the line joining the points [tex]$(3,7)$[/tex] and [tex]$(4,-8)$[/tex]?

A. -15
B. -1
C. [tex]$-\frac{1}{7}$[/tex]
D. [tex]$\frac{21}{32}$[/tex]
E. 15



Answer :

To determine the slope of the line that passes through the points [tex]\((3, 7)\)[/tex] and [tex]\((4, -8)\)[/tex], we use the slope formula:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]
Here, [tex]\((x_1, y_1)\)[/tex] are the coordinates of the first point and [tex]\((x_2, y_2)\)[/tex] are the coordinates of the second point. Plugging in the values from the given points:
[tex]\[ x_1 = 3, \quad y_1 = 7, \quad x_2 = 4, \quad y_2 = -8 \][/tex]

Substituting these values into the slope formula gives:
[tex]\[ m = \frac{-8 - 7}{4 - 3} \][/tex]

Now, calculate the differences in the numerator and the denominator:
[tex]\[ -8 - 7 = -15 \][/tex]
[tex]\[ 4 - 3 = 1 \][/tex]

So the slope [tex]\(m\)[/tex] is:
[tex]\[ m = \frac{-15}{1} = -15 \][/tex]

Therefore, the slope of the line joining the points [tex]\((3, 7)\)[/tex] and [tex]\((4, -8)\)[/tex] is:
[tex]\[ \boxed{-15} \][/tex]