What is the equation of the line, in slope-intercept form, that contains the points (-1,8) and (2,-1)? a) y= -3x +5 b) y= -x+5 c) y= x+5 d) y= -x+3

Y-yo = m (x-xo)
 We must find the slope of the line:
 m = (y2-y1) / (x2-x1)
 m = (- 1-8) / (2 - (- 1))
 m = (- 9) / (3)
 m = -3
 The ordered pair is:
 (xo, yo) = (- 1, 8)
 Substituting:
 y-8 = -3 (x + 1)
 Rewriting:
 y = -3x-3 + 8
 y = -3x + 5

 
 The equation of the line is:
 A) y = -3x +5

No a triangle cannot be formed because when you add the two smallest number together (which would be 11) the have to be bigger than the number it is "against" ( which would be 12)