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D( x )
(x^2-9)^2 = 0
x^2-9 = 0
(x^2-9)^2 = 0
(x^2-9)^2 = 0
1*x^2 = 9 // : 1
x^2 = 9
x^2 = 9 // ^ 1/2
abs(x) = 3
x = 3 or x = -3
x^2-9 = 0
x^2-9 = 0
1*x^2 = 9 // : 1
x^2 = 9
x^2 = 9 // ^ 1/2
abs(x) = 3
x = 3 or x = -3
x in (-oo:-3) U (-3:3) U (3:+oo)
(4*x)/(x^2-9)-((4*x^3)/((x^2-9)^2)) = 0
(4*x)/(x^2-9)-4*x^3*(x^2-9)^-2 = 0
(4*x)/(x^2-9)+(-4*x^3)/((x^2-9)^2) = 0
(4*x*(x^2-9))/((x^2-9)^2)+(-4*x^3)/((x^2-9)^2) = 0
4*x*(x^2-9)-4*x^3 = 0
-36*x = 0
(-36*x)/((x^2-9)^2) = 0
(-36*x)/((x^2-9)^2) = 0 // * (x^2-9)^2
-36*x = 0
-36*x = 0 // : -36
x = 0
x = 0
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