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D( f )
f = 0
f = 0
f = 0
f in (-oo:0) U (0:+oo)
19/f-f+7/8-8 = 0
19*f^-1-1*f^1-57/8*f^0 = 0
(19*f^0-1*f^2-57/8*f^1)/(f^1) = 0 // * f^2
f^1*(19*f^0-1*f^2-57/8*f^1) = 0
f^1
(-57/8)*f-f^2+19 = 0
(-57/8)*f-f^2+19 = 0
DELTA = (-57/8)^2-(-1*4*19)
DELTA = 8113/64
DELTA > 0
f = ((8113/64)^(1/2)-(-57/8))/(-1*2) or f = (-(-57/8)-(8113/64)^(1/2))/(-1*2)
f = ((8113/64)^(1/2)+57/8)/(-2) or f = (57/8-(8113/64)^(1/2))/(-2)
f in { ((8113/64)^(1/2)+57/8)/(-2), (57/8-(8113/64)^(1/2))/(-2)}
f in { ((8113/64)^(1/2)+57/8)/(-2), (57/8-(8113/64)^(1/2))/(-2) }
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