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D( t )
t^2 = 0
t = 0
t^2 = 0
t^2 = 0
1*t^2 = 0 // : 1
t^2 = 0
t = 0
t = 0
t = 0
t in (-oo:0) U (0:+oo)
4/t-(9/(t^2)) = 0
4/t-9*t^-2 = 0
4*t^-1-9*t^-2 = 0
t_1 = t^-1
4*t_1^1-9*t_1^2 = 0
4*t_1-9*t_1^2 = 0
DELTA = 4^2-(-9*0*4)
DELTA = 16
DELTA > 0
t_1 = (16^(1/2)-4)/(-9*2) or t_1 = (-16^(1/2)-4)/(-9*2)
t_1 = 0 or t_1 = 4/9
t_1 = 0
t^-1+0 = 0
t^-1 = 0
1*t^-1 = 0 // : 1
t^-1 = 0
t należy do O
t_1 = 4/9
t^-1-4/9 = 0
1*t^-1 = 4/9 // : 1
t^-1 = 4/9
-1 < 0
1/(t^1) = 4/9 // * t^1
1 = 4/9*t^1 // : 4/9
9/4 = t^1
t = 9/4
t = 9/4
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