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D( k )
k = 0
k = 0
k = 0
k in (-oo:0) U (0:+oo)
1/8 = k-(10/k) // - k-(10/k)
10/k-k+1/8 = 0
10*k^-1-1*k^1+1/8*k^0 = 0
(1/8*k^1-1*k^2+10*k^0)/(k^1) = 0 // * k^2
k^1*(1/8*k^1-1*k^2+10*k^0) = 0
k^1
(1/8)*k-k^2+10 = 0
(1/8)*k-k^2+10 = 0
DELTA = (1/8)^2-(-1*4*10)
DELTA = 2561/64
DELTA > 0
k = ((2561/64)^(1/2)-(1/8))/(-1*2) or k = (-(1/8)-(2561/64)^(1/2))/(-1*2)
k = ((2561/64)^(1/2)-1/8)/(-2) or k = ((2561/64)^(1/2)+1/8)/2
k in { ((2561/64)^(1/2)-1/8)/(-2), ((2561/64)^(1/2)+1/8)/2}
k in { ((2561/64)^(1/2)-1/8)/(-2), ((2561/64)^(1/2)+1/8)/2 }
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