( 8x /(x² -64) - 7/(8+x) ) *(3x-24) / (x+56) =
( 8x /(x -8)(x+8) - 7/(x+8) ) *3(x-8) / (x+56) =
( (8x -7(x-8) ) / (x -8)(x+8) * (3(x -8) / (x+56)) =
( (8x -7x+56) ) / (x -8)(x+8) * (3(x -8) / (x+56)) =
(x+56) / (x -8)(x+8) * 3(x -8) / (x+56) =
(x+56)*3(x-8) / (x -8)(x+8) (x+56) = 3/(x - 8) .
* * * * * * * * * * * * * * * * * * * * *
Если (3x -7)/(4-5x) = 9
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(3x -7)/(4-5x) =9 ⇔(3x -7)/-(5x- 4 ) =9 ⇔ -(3x -7)/ (5x -4) = 9 ⇔
(3x -7)/ (5x -4) = -9 .
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(3x -7)/(4-5x) =9 ⇔ 4*(3x -7)/(4-5x) =4*9 ⇔ (12x -28)/(4 -5x) = 36 .
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(3x -7)/(4-5x) =9 ⇔ (4-5x) /(3x -7)= 1/9 ⇒(4-5x) /(3x -7) - 8 = 1/9 -8 = -7 8/9