Question

Complete the equation of the line through

(-8,8) and (1,-10).
use exact numbers
Y=

Answer 1

Explanation:

Find the equation of the line thru the points (2,1) and (3,5)

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This is a 2 step process. First find the slope of the line thru the points.

slope, m = diffy/diffx

m = (5-1)/(3-2)

m = 4

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Now use y = mx + b with either point to find b, the y-intercept.

y = mx + b

5 = 4*3 + b

b = -7

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Answer 2

Explanation:

Formula for calculating the equation of a line is expressed as shown below;

y = mx+c OR y-y1 = m(x-x1) where

m is the slope or gradient

c is the intercept (the point where the line cuts the y axis)

m = ∆y/∆x

m = y2-y1/x2-x1

Given the points (-8,8) and (1,-10).

x1 = -8, y1 = 8, x2 = 1, y2 = -10

m = -10-8/1-(-8)

m = -18/9

m = -2

The equation of a line can also be written as a point slope:

y-y1 = m(x-x1)

Substituting the value of x1, y1 and m into the equation we have;

y-8 = -2(x-(-8))

y-8 = -2(x+8)

y-8 = -2x-16

y= -2x-16+8

y = -2x-8

The equation of the line is y = -2x-8