Write an equation for a line passing through the points (-1,8 and (0,5)

Answer 1

The two-point form of a straight line:

y - y1 = ( y2 - y1 ) ( x - x1 ) / ( x2 - x1 )

In this case:

x1 = 1 , y1 = - 8

x2 = 0 , y2 = 5

y - y1 = ( y2 - y1 ) ( x - x1 ) / ( x2 - x1 )

y - ( - 8 ) = [ 5 - ( - 8 ) ] ∙ ( x - 1 ) / ( 0 - 1 )

y + 8 = ( 5 + 8 ) ∙ ( x - 1 ) / - 1

y + 8 = 13 ∙ ( x - 1 ) / - 1

y + 8 = - 13 ∙ ( x - 1 )

y + 8 = - 13 ∙ x - 13 ∙ ( -1 )

y + 8 = - 13 x + 13

Subtract 8 to both sides

y = - 13 x + 5