How do you find the equation of a straight line given only the points of 3 -4 and -1 -2?

Answer 1

There are probably several methods; here is one.

First, find the slope between the two points (difference of y divided by difference of x, between the two points). Then write the equation for the line in the form

y = mx + b

(where m is the slope, and b is the y-intercept). Replace the slope, and the coordinates for one of the points, and solve for b. Write the slope-intercept equation (y = mx + b) again, this time replacing only m and b for the calculated values.

Another answer:-

As the previous contributor correctly points out there are several methods and one method is as follows:

First we have to find the slope of the line so let points (3, -4) and (-1, -2) be called (x1 y1) and (x2 y2)

Slope = y2-y1 over x2-x1 = -2-(-4) over -1-3 = -1/2

Equation of a straight line: y = mx+c where m is the slope and c is the intercept on the y axis.

So using points (3, -4) -1/2*3+c = -4

-3/2+c = -4

c = -4+3/2

c = -5/2

Therefore the straight line equation is: y = -1/2x-5/2 or 2y = -x-5

If the other points of (-1, -2) were used the result would be the same.