4/5=v-3/v

Solution for 4/5=v-3/v equation:

D( v )

v = 0

v = 0

v = 0

v in (-oo:0) U (0:+oo)

4/5 = v-(3/v) // - v-(3/v)

3/v-v+4/5 = 0

3*v^-1-1*v^1+4/5*v^0 = 0

(4/5*v^1-1*v^2+3*v^0)/(v^1) = 0 // * v^2

v^1*(4/5*v^1-1*v^2+3*v^0) = 0

v^1

(4/5)*v-v^2+3 = 0

(4/5)*v-v^2+3 = 0

DELTA = (4/5)^2-(-1*3*4)

DELTA = 316/25

DELTA > 0

v = ((316/25)^(1/2)-(4/5))/(-1*2) or v = (-(4/5)-(316/25)^(1/2))/(-1*2)

v = ((316/25)^(1/2)-4/5)/(-2) or v = ((316/25)^(1/2)+4/5)/2

v in { ((316/25)^(1/2)-4/5)/(-2), ((316/25)^(1/2)+4/5)/2} 

v in { ((316/25)^(1/2)-4/5)/(-2), ((316/25)^(1/2)+4/5)/2 }