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D( x )
x^2 = 0
x^2 = 0
x^2 = 0
1*x^2 = 0 // : 1
x^2 = 0
x = 0
x in (-oo:0) U (0:+oo)
4*x-(256/(x^2)) = 0
4*x-256*x^-2 = 0
4*x^1-256*x^-2 = 0
(4*x^3-256*x^0)/(x^2) = 0 // * x^4
x^2*(4*x^3-256*x^0) = 0
x^2
4*x^3-256 = 0
{ 1, -1, 2, -2, 4, -4, 8, -8, 16, -16, 32, -32, 64, -64, 128, -128, 256, -256 }
1
x = 1
4*x^3-256 = -252
1
-1
x = -1
4*x^3-256 = -260
-1
2
x = 2
4*x^3-256 = -224
2
-2
x = -2
4*x^3-256 = -288
-2
4
x = 4
4*x^3-256 = 0
4
x-4
4*x^2+16*x+64
4*x^3-256
x-4
16*x^2-4*x^3
16*x^2-256
64*x-16*x^2
64*x-256
256-64*x
0
4*x^2+16*x+64 = 0
DELTA = 16^2-(4*4*64)
DELTA = -768
DELTA < 0
x in { 4}
x = 4
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