Question 834615
{{{x[0]=1}}}
{{{v[0]=35}}}
{{{x[1]=0}}}
{{{a=-9.8}}}
{{{x=x0+v0*t+(1/2)at^2}}}
{{{-4.9t^2+35t+1=0}}}
{{{t = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{t = (-35 +- sqrt( (35)^2-4*(-4.9)*1 ))/(2*(-4.9)) }}}  
{{{t = (-35 +- sqrt( 1225+19.6))/(-9.8) }}}
{{{t = (-35 +- sqrt( 1244.6))/(-9.8) }}} 
Only positive time values make sense for this problem.
{{{t = (-35 - sqrt( 1244.6))/(-9.8) }}}
{{{t = (-70.28)/(-9.8) }}}
{{{t = 7.2 }}}
7.2 seconds.