Question

http://static.k12.com/calms_media/media/308500_309000/308808/1/c9ddd235e76faa5f12cc74a55ca077ec292fb734/MS_ALG_S1_07_10_quiz_Q4_question.gif

Which is the equation of the given line in slope-intercept form?

A. y = 3x - 1

B. y = - 1/3x - 1

C. y = - 3x - 1

D. y = 3x + 1

Explain please.

Answer 1

that line passes through the points of (-1,2) and (1,-4). use the formula :
(y -y1)/(y2-y1) = (x - x1)/(x2-x1)

Answer 2

apply all points into formula above
(y -y1)/(y2-y1) = (x - x1)/(x2-x1)
(y - 2)/(-4 - 2) = (x - (-1))/(1 - (-1))
(y - 2)/-6 = (x +1)/2
cross multiplication, then simplify get
2(y-2) = -6(x+1)
2y - 4 = -6x - 6
add by 4 on both sides, get
2y - 4 + 4 = -6x - 6 + 4
2y = -6x -2
divided by 2 on both sides, get
2y/2 = (-6x-2)/2
y = -3x - 1

that is the line in the slope intercept form

Answer 3

so, it is C

Answer 4

ok thanks!