Question

What is the equation of the following line written in general form? (4,5) (1,2) A y - X+1=0 B X-y + 1 = 0 C -X-y + 1 = 0

Answer 1

First we have to calculate the slope of the line with points (4,5) (1,2)

x1= 4 , x2=1, y1=5, y2=2

$m=\frac{y2-y1}{x2-x1}=\frac{2-5}{1-4}=\frac{-3}{-3}=1$

Then we have to calculate the y-intercept with equation y=mx + b. Replacing

x=4 and y= 5

5 = (1 )*(4) + b Isolating b, we have

5 - 4 = b

1 = b

The slope-intercept form is

y= x + 1

Transposing x and 1 to the other side we get the general form of the line

y - x - 1 = 0. It can be written also as -y + x + 1 = 0. The answer would be option B.