Question

La ecuación de la recta que pasa por los puntos (2,-1) y (1,-5) es:

Answer 1

Given:

A line passes through the points (2,-1) and (1,-5).

To find:

The equation of the line.

Solution:

If a line passes through the two points, then the equation of the line is

$y-y_1=\dfrac{y_2-y_1}{x_2-x_1}(x-x_1)$

The line passes through the points (2,-1) and (1,-5). So, the equation of the line is

$y-(-1)=\dfrac{-5-(-1)}{1-2}(x-2)$

$y+1=\dfrac{-5+1}{-1}(x-2)$

$y+1=\dfrac{-4}{-1}(x-2)$

$y+1=4(x-2)$

Using distributive property, we get

$y+1=4(x)+4(-2)$

$y+1=4x-8$

Subtract 1 from both sides.

$y+1-1=4x-8-1$

$y=4x-9$

Therefore, the correct option is B.