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y intercept of line

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

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Francisco E. | Francisco; Civil Engineering, Math., Science, Spanish, Computers.Francisco; Civil Engineering, Math., Sci...
5.0 5.0 (1 lesson ratings) (1)
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Carol H. | Experienced Mathematics Tutor w/ Master's Degree in MathExperienced Mathematics Tutor w/ Master'...
4.9 4.9 (268 lesson ratings) (268)
0
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