Question

A line passes through the points (-6, 4) and (-2, 2). Which is the equation of the line?
O y--3x+1
O y-5x+7
O y = -2x - 8
O y = 2x + 16

Answer 1

Answer:

$\displaystyle y=-\frac{1}{2}x+1$

Step-by-step explanation:

The equation of any line in slope-intercept form is:

y=mx+b

Being m the slope and b the y-intercept.

Assume we know the line passes through points A(x1,y1) and B(x2,y2). The slope can be calculated with the equation:

$\displaystyle m=\frac{y_2-y_1}{x_2-x_1}$

Two points are given: (-6,4) and (-2,2). Calculating the slope:

$\displaystyle m=\frac{2-4}{-2+6}=\frac{-2}{4}=-\frac{1}{2}$

The equation of the line is, so far:

$\displaystyle y=-\frac{1}{2}x+b$

To calculate the value of b, we use any of the given points, for example (-6,4):

$\displaystyle 4=-\frac{1}{2}(-6)+b$

$\displaystyle 4=3+b$

Solving:

b = 1

The equation of the line is:

$\boxed{\displaystyle y=-\frac{1}{2}x+1}$

We can see none of the choices is correct.