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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
0.16/x < 0.4 // - 0.4
0.16/x-0.4 < 0
0.16*x^-1 < 0.4
0.16*x^-1 < 0.4 // : 0.16
x^-1 < 0.4/0.16
x^-1 < 2.5
1/(x^1) < 2.5
x <> 0
1/(x^1) < 2.5 // * x^2
(x^2)/(x^1) < 2.5*x^2
x^1 < 2.5*x^2
x-2.5*x^2 < 0
x^1*(1-2.5*x) < 0
x < 0
-(abs(x))^1*(2.5*(abs(x))^1+1) < 0 // : -(abs(x))^1
2.5*(abs(x))^1+1 > 0
2.5*(abs(x))^1 > -1 // : 2.5
(abs(x))^1 > -1/2.5
(abs(x))^1 > -0.4 // ^ 1/1
abs(x) > (-0.4)^(1/1)
abs(x) > -0.4
x in (-oo:0)
x < 0
x > 0
x^1*(1-(2.5*x^1)) < 0 // : x^1
1-(2.5*x^1) < 0
1 < 2.5*x^1 // : 2.5
1/2.5 < x^1 // ^ 1/1
(1/2.5)^(1/1) < x
x in (0.4:+oo)
x > 0
x in (-oo:0) U (0.4:+oo)
x in (-oo:0) U (0.4:+oo)
(-oo:0) U (0.4:+oo)
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