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D( x )
(0.4-x)^2 = 0
x^2 = 0
(0.4-x)^2 = 0
(0.4-x)^2 = 0
0.4-x = 0 // - 0.4
-x = -0.4 // * -1
x = 0.4
x^2 = 0
x^2 = 0
1*x^2 = 0 // : 1
x^2 = 0
x = 0
x in (-oo:0) U (0:0.4) U (0.4:+oo)
(2*19)/(x^2) = (3*19)/((0.4-x)^2) // - (3*19)/((0.4-x)^2)
(2*19)/(x^2)-((3*19)/((0.4-x)^2)) = 0
(2*19)/(x^2)-57*(0.4-x)^-2 = 0
38/(x^2)-57/((0.4-x)^2) = 0
(-57*x^2)/(x^2*(0.4-x)^2)+(38*(0.4-x)^2)/(x^2*(0.4-x)^2) = 0
38*(0.4-x)^2-57*x^2 = 0
6.08-19*x^2-30.4*x = 0
6.08-19*x^2-30.4*x = 0
6.08-19*x^2-30.4*x = 0
DELTA = (-30.4)^2-(-19*4*6.08)
DELTA = 30.4^2+462.08
DELTA = 1386.24
DELTA > 0
x = ((30.4^2+462.08)^(1/2)+30.4)/(-19*2) or x = (30.4-(30.4^2+462.08)^(1/2))/(-19*2)
x = ((30.4^2+462.08)^(1/2)+30.4)/(-38) or x = (30.4-(30.4^2+462.08)^(1/2))/(-38)
(x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)))*(x-((30.4-(30.4^2+462.08)^(1/2))/(-38))) = 0
((x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)))*(x-((30.4-(30.4^2+462.08)^(1/2))/(-38))))/(x^2*(0.4-x)^2) = 0
((x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)))*(x-((30.4-(30.4^2+462.08)^(1/2))/(-38))))/(x^2*(0.4-x)^2) = 0 // * x^2*(0.4-x)^2
(x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)))*(x-((30.4-(30.4^2+462.08)^(1/2))/(-38))) = 0
( x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)) )
x-(((30.4^2+462.08)^(1/2)+30.4)/(-38)) = 0 // + ((30.4^2+462.08)^(1/2)+30.4)/(-38)
x = ((30.4^2+462.08)^(1/2)+30.4)/(-38)
( x-((30.4-(30.4^2+462.08)^(1/2))/(-38)) )
x-((30.4-(30.4^2+462.08)^(1/2))/(-38)) = 0 // + (30.4-(30.4^2+462.08)^(1/2))/(-38)
x = (30.4-(30.4^2+462.08)^(1/2))/(-38)
x in { ((30.4^2+462.08)^(1/2)+30.4)/(-38), (30.4-(30.4^2+462.08)^(1/2))/(-38) }
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