( 2 / ( X^2 - 3X)) - ( 1 / ( X + 3 )) = 12 / X^3 - 9X
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X^2 - 3X = X * ( X - 3 )
( X + 3 )
X^3 - 9X = X * ( X^2 - 9 ) = X * ( X - 3 ) * ( X + 3 ) общий знаменатель
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2 * ( X + 3 ) - X * ( X - 3 ) = 12
2X + 6 - X^2 + 3X = 12
5X + 6 - X^2 = 12
X^2 - 5X + 6 = 0
D = 25 - 24 = 1 ; √ D = 1
X1 = ( 5 + 1 ) : 2 = 3
X2 = ( 5 - 1 ) : 2 = 2
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X * ( X - 3) * ( X + 3 ) ≠ 0
X ≠ 0
X ≠ 3
X ≠ - 3
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ОТВЕТ : Х = 2