direct variation
u=kv
6=k(-7)
k=-6/7
u=kv
u =-6/7 * 4
u =-24/7
Answer: u = -24/7 or -3 3/7
Since u varies directly with v, then
u = kv ( k is the constant of variation )
to find k use u = 6 when v = - 7
k = [tex]\frac{u}{v}[/tex] = [tex]\frac{6}{-7}[/tex] = - [tex]\frac{6}{7}[/tex]
thus u = - [tex]\frac{6}{7}[/tex] v
when v = 4, then
u = - [tex]\frac{6}{7}[/tex] × 4 = - [tex]\frac{24}{7}[/tex]
