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