Question

Find the equation (in terms of x ) of the line through the points (-3,4) and (1,-8)

Answer 1

y = -3x - 5

Explanation:

-3, 4 and 1, -8

1 - -3 = 4

-8 - 4 = -12

`(-12)/(4)` =
`(-3)/(1)` = -3

gradient/slope = -3

now substituting in the point -3, 4 to find the y intercept:

4= -3 x -3 + c

4 = 9 + c

-5 = c

y intercept = -5

equation is y = -3x - 5

Answer 2

A(-3,4) B(1,-8)

y-y1/x-x1 =y2-y1/x2-x1

y-4/x--3 = -8-4/1--3

y-4/x+3 = -12/1+3

y-4/x+3 =-12/4

y-4/x+3 = -3

y-4 = -3(x+3)

y-4=-3x-9

y+3x +9-4=

y+3x+5=0