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D( x )
(0.2-x)^2 = 0
(0.2-x)^2 = 0
(0.2-x)^2 = 0
0.2-x = 0 // - 0.2
-x = -0.2 // * -1
x = 0.2
x in (-oo:0.2) U (0.2:+oo)
49.5 = (2*x)/((0.2-x)^2) // - (2*x)/((0.2-x)^2)
49.5-((2*x)/((0.2-x)^2)) = 0
49.5-2*x*(0.2-x)^-2 = 0
(-2*x)/((0.2-x)^2)+49.5 = 0
(-2*x)/((0.2-x)^2)+(49.5*(0.2-x)^2)/((0.2-x)^2) = 0
49.5*(0.2-x)^2-2*x = 0
49.5*x^2-21.8*x+1.98 = 0
49.5*x^2-21.8*x+1.98 = 0
49.5*x^2-21.8*x+1.98 = 0
DELTA = (-21.8)^2-(1.98*4*49.5)
DELTA = 21.8^2-392.04
DELTA = 83.2
DELTA > 0
x = ((21.8^2-392.04)^(1/2)+21.8)/(2*49.5) or x = (21.8-(21.8^2-392.04)^(1/2))/(2*49.5)
x = ((21.8^2-392.04)^(1/2)+21.8)/99 or x = (21.8-(21.8^2-392.04)^(1/2))/99
(x-((21.8-(21.8^2-392.04)^(1/2))/99))*(x-(((21.8^2-392.04)^(1/2)+21.8)/99)) = 0
((x-((21.8-(21.8^2-392.04)^(1/2))/99))*(x-(((21.8^2-392.04)^(1/2)+21.8)/99)))/((0.2-x)^2) = 0
((x-((21.8-(21.8^2-392.04)^(1/2))/99))*(x-(((21.8^2-392.04)^(1/2)+21.8)/99)))/((0.2-x)^2) = 0 // * (0.2-x)^2
(x-((21.8-(21.8^2-392.04)^(1/2))/99))*(x-(((21.8^2-392.04)^(1/2)+21.8)/99)) = 0
( x-(((21.8^2-392.04)^(1/2)+21.8)/99) )
x-(((21.8^2-392.04)^(1/2)+21.8)/99) = 0 // + ((21.8^2-392.04)^(1/2)+21.8)/99
x = ((21.8^2-392.04)^(1/2)+21.8)/99
( x-((21.8-(21.8^2-392.04)^(1/2))/99) )
x-((21.8-(21.8^2-392.04)^(1/2))/99) = 0 // + (21.8-(21.8^2-392.04)^(1/2))/99
x = (21.8-(21.8^2-392.04)^(1/2))/99
x in { ((21.8^2-392.04)^(1/2)+21.8)/99, (21.8-(21.8^2-392.04)^(1/2))/99 }
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