Question

How do you write an equation of a line given 2 points?

Write the equation for the line containing points (3,8) and (9,2).

Convert the equation to slope intercept form.

Answer 1

Slope intercept form: y=mx+b

Use this (y2-y1)/(x2-x1) to find slop.

(2-8)/(9-3) = -1

M is slope so m = -1

Y=mx+b

Y= -1x+b

Sub into any point (3,8) or (9,2)

Y=-1x+b
8= -1(3) +b
8= -3 +b
10= b

Y= -1x+10

Answer 2

x+y=11

y=-x+11

Explanation:

In order to solve this we first have to find the slope of the function, remember the formula of the slope:

`Slope=(y2-y1)/(x2-x1)\\ Slope=(2-3)/(9-8)\\ Slope=(-1)/(1)\\ Slope=-1`

The slope is -1, based on this we can calculate the formula for the equation with the general function:

y-y1= M(x-x1)

y-8=-1(x-3=

y-8=-x+3

y+x-11=0

Now in the slope form you just clear y from the equation:

y=-2-x+11

So that is the answer to the question.