y intercept of line

Question

What is the y-intercept of the line (-10,-4) (-2,1) ?

Answer 1

The slope of the line will be

(1+4)/(-2+10) = 5/8

The slope intersect form will be

Y=(5/8)x + b

plugging any one of the two points we have

1=(5/8)(-2) + b

b=1+(5/4)

b= 9/4

Check

-4=(5/8)(-10) +(9/4)

-4 = -4

Check!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 2

First, you need to find the equation of the line. 

The form of the equation of a line given two points is the following:

 

(y-y₁)/x-x₁₎ = (y₂-y₁)/(x₂-x₁)  Let x₁ = -10, y₁ = -4, x₂ = -2, and y₂ = 1.

 

Substituting into the equation:

y-(-4) =   1-(-4)   

x-(-10)  -2-(-10)

 

 y+4     = 5     Cross multiply:

x+10       8

 

8y + 32 = 5x + 50   Solve for y:

 

8y = 5x + 18

 

y = 5 x + 18

      8        8

 

y = 5 x + 9   Since this equation is now in slope-intercept form, y = mx + b, the y=intercept is 9/4 or 2 1/4.

      8       4