Persistent? Let's find the imaginary roots...
10v^2+4v+70=0
10v^2+4v=-70
v^2+2v/5=-7
v^2+2v/5+1/25=-7+1/25
(v+1/5)^2=-174/25
v+1/5=(+-)i(174)^(1/2)/5
v=(-1+i(174^.5)/5) and (-1-i(174^.5))/5
note the "i" in both factors...these are imaginary units and if you were to graph the original expression you would see that the curve never touches the x axis...
