(2011•青海)请你先化简分式x+3x
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(2011•青海)请你先化简分式
x+3 |
x
x+3
x2−1÷ x2+6x+9 x2−2x+1+ 1 x+1 = x+3 (x+1)(x−1)• (x−1)2 (x+3)2+ 1 x+1 = 1 x+1• x−1 x+3+ 1 x+1 = 1 x+1( x−1 x+3+1) = 1 x+1• 2(x+1) x+3 = 2 x+3, ∵x2-1≠0,x+3≠0,x-1≠0,x+1≠0, ∴取x=2, 代入得:原式= 2 2+3= 2 5. |