algebra
posted by Eya .
i really your need help,i don't understand the problem. The velocity of a blood corpuscle in a vessel depends on how far the corpuscle is from the center of the vessel. Let R be the constant radius of the vessel; Vm, the constant maximum velocity of the corpuscle; r, the distance from the center to a particular blood corpuscle (variable); and Vr, the velocity of that corpuscle. The velocity Vr is related to the distance r by the equation Vr=Vm (1r^2 /R^2). Find r when Vr=1/4Vm.

just plug it in:
1/4 Vm = Vm(1r^2/R^2)
1 = 4  4r^2/R^2
4r^2/R^2 = 3
r^2 = 3/4R^2
r = √3/2 R