(3)
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5/(2x² -x -3) = 5/(x+1)(2x -3) = (2(x+1) - (2x -3) ) / (x+1)(2x -3) =
2(x+1) / (x+1)(2x -3) - (2x -3) / (x+1)(2x -3) = 2/(2x -3) - 1/(x+1) .
* * * ax² +bx +c =a(x -x₁)(x -x₂) ; 2x² -x -3 =2(x+1)(x -3/2) = (x+1)(2x -3) * * *
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5/(x+1)(2x -3) = m /(x+1) +n /(2x-3) = ( (2m+n)*x +(-3m+n) ) / (x+1)(2x -3) .
5 ≡ (2m+n)*x +(-3m+n)
{ 2m+n =0 ; - 3m+n =5 . ⇔ { m = -1 ; n =2 .
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