How do you write the equation in slope intercept form given (2, 2), (-1, 4)?

2 Answers
Jul 6, 2016

The slope-intercept form of the equation is y=-2/3x+10/3

Explanation:

The slope-intercept form of the equation of the line is y=mx+b
where m= slope and b= the y intercept

m=(y_2-y_1)/(x_2-x_1)

x_1=2
y_1=2
x_2=-1
y_2=4

m = (4-2)/(-1-2)

m = (2)/(-3)

m=-2/3

Now use the point slope formula to solve for the equation of the line.

(y-y_1)=m(x-x_1)

For this situation we are given the slope of 3 and a point of (2,1)

m=-2/3
x_1=2
y_1=2

(y-y_1)=m(x-x_1)

(y-2)=-2/3(x-2)

y-2=-2/3x-4/3

y cancel(-2) cancel(+2)=-2/3x+4/3 + 2

y=-2/3x+4/3 +6/3

y=-2/3x+10/3

Jul 6, 2016

y = (-2x)/3 +10/3

Explanation:

If you have two points on a straight line, there is a lovely formula which allows you to get the equation immediately. It is based on the formula for the slope, so you kill two birds with one stone!

(y-y_1)/(x-x_1) = (y_2-y_1)/(x_2-x_1)

(y-2)/(x-2) = (4-2)/(-1-2) = 2/-3 " this value is the slope"

(y-2)/(x-2) = -2/3" cross multiply"

3y - 6 = -2x +4

3y = -2x +10

y = (-2x)/3 +10/3