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640=-16t^2
We move all terms to the left:
640-(-16t^2)=0
We get rid of parentheses
16t^2+640=0
a = 16; b = 0; c = +640;
Δ = b2-4ac
Δ = 02-4·16·640
Δ = -40960
Delta is less than zero, so there is no solution for the equation
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