Question

A direct variation function contains the points (–8, –6) and (12, 9). Which equation represents the function?

y = –negative StartFraction 4 Over 3 EndFraction equals StartFraction 4 Over 3 EndFractionx
y = –k equals negative StartFraction 3 Over 4 EndFraction x.x
y = k equals StartFraction 3 Over 4 EndFraction x.x
y = k equals StartFraction 4 Over 3 EndFraction x.x

Answer 1

y = (3/4)x

Because for a direct variation y = kx, k = y/x. From (12, 9): k = 9/12 = 3/4 (and from (−8, −6): k = −6/−8 = 3/4).