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t in (-oo:+oo)
9.8*(1/2)*t^2-(0.259*4.87*t)-0.28 = 0
9.8*(1/2)*t^2-1.26133*t-0.28 = 0
4.9*t^2-1.26133*t-0.28 = 0
DELTA = (-1.26133)^2-(-0.28*4*4.9)
DELTA = 1.26133^2+5.488
DELTA = 7.07895337
DELTA > 0
t = ((1.26133^2+5.488)^(1/2)+1.26133)/(2*4.9) or t = (1.26133-(1.26133^2+5.488)^(1/2))/(2*4.9)
t = 0.10204082*((1.26133^2+5.488)^(1/2)+1.26133) or t = 0.10204082*(1.26133-(1.26133^2+5.488)^(1/2))
t in { 0.10204082*(1.26133-(1.26133^2+5.488)^(1/2)), 0.10204082*((1.26133^2+5.488)^(1/2)+1.26133) }
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