Write an equation of the line that passes through the pair of points [tex][tex]$(-2, -2)$[/tex][/tex] and [tex]$(5, -5)$[/tex].

A. [tex]y = \frac{3}{7} x - \frac{20}{7}[/tex]
B. [tex]y = -\frac{3}{7} x + \frac{20}{7}[/tex]
C. [tex]y = -\frac{3}{7} x + \frac{7}{20}[/tex]
D. [tex]y = -\frac{3}{7} x - \frac{20}{7}[/tex]



Answer :

To determine the equation of the line that passes through the points [tex]\((-2, -2)\)[/tex] and [tex]\( (5, -5) \)[/tex], we follow these steps:

1. Calculate the slope [tex]\( m \)[/tex]:
The formula for the slope [tex]\( m \)[/tex] between two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

For the given points [tex]\((-2, -2)\)[/tex] and [tex]\( (5, -5) \)[/tex]:
[tex]\[ m = \frac{-5 - (-2)}{5 - (-2)} = \frac{-5 + 2}{5 + 2} = \frac{-3}{7} = -\frac{3}{7} \][/tex]

2. Find the y-intercept [tex]\( b \)[/tex]:
The equation of the line in slope-intercept form is:
[tex]\[ y = mx + b \][/tex]
To find [tex]\( b \)[/tex], we can use the slope [tex]\( m \)[/tex] and one of the given points. Let's use the point [tex]\( (-2, -2) \)[/tex] for this purpose:
[tex]\[ y_1 = mx_1 + b \][/tex]
Substituting the values [tex]\((-2, -2)\)[/tex] and [tex]\( m = -\frac{3}{7} \)[/tex]:
[tex]\[ -2 = -\frac{3}{7}(-2) + b \][/tex]
Simplify the equation:
[tex]\[ -2 = \frac{6}{7} + b \][/tex]
Solving for [tex]\( b \)[/tex]:
[tex]\[ b = -2 - \frac{6}{7} = -\frac{14}{7} - \frac{6}{7} = -\frac{20}{7} \][/tex]

3. Form the equation of the line:
Now that we have the slope [tex]\( m = -\frac{3}{7} \)[/tex] and the y-intercept [tex]\( b = -\frac{20}{7} \)[/tex], we can write the equation of the line:
[tex]\[ y = -\frac{3}{7}x - \frac{20}{7} \][/tex]

From the given options, the one that matches this equation is:

d. [tex]\( y = -\frac{3}{7}x - \frac{20}{7} \)[/tex]

Thus, the equation of the line that passes through the points [tex]\((-2, -2)\)[/tex] and [tex]\( (5, -5) \)[/tex] is:
d. [tex]\( y = -\frac{3}{7} x - \frac{20}{7} \)[/tex].

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