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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
8.1 = (1836-x)/x // - (1836-x)/x
8.1-((1836-x)/x) = 0
(-1*(1836-x))/x+8.1 = 0
(-1*(1836-x))/x+(8.1*x)/x = 0
8.1*x-1*(1836-x) = 0
9.1*x-1836 = 0
(9.1*x-1836)/x = 0
(9.1*x-1836)/x = 0 // * x
9.1*x-1836 = 0
9.1*x-1836 = 0 // + 1836
9.1*x = 1836 // : 9.1
x = 1836/9.1
x = 201.75824176
x = 201.75824176
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