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解下列方程 (1)x²-2x-8=0 (2)x²+5+...

0.8x(0.5+x)=1.2 0.4+ 0.8x =1.2 0.8x = 0.8 x=1 检验 0.8*(0.5+1)=0.8*1.5 = 1.2(等于方程右侧)

x+2/3-x²-3/2=2 →x²-x+17/6=0 ∴x=无解 2.(x+5)²-2(x+5)-8=0 →﹙x+5+2﹚﹙x+5-4﹚=0 ∴x1=-7; x2=-1 3.(x+3)(x-1)=5 →x²+2x-8=0 ∴﹙x-2﹚﹙x+4﹚=0 ∴x1=-4; x2=2 4.(x+1)(x+2)=(2x-1)(x+1...

(x-2)(x-3)=12 x^2-5x+6=12 x^2-5x-6=0 (x-6)(x+1)=0 x1=6 x2=-1 (x-2)²=(2x+3)² x-2=±(2x+3) x-2=2x+3 或 x-2=-2x-3 -x=2+3 或 3x=-1 x1=-5 x2=-1/3 x²-5根号2+8=0 x²=8-5根号2 x=±根号(8-5根号2)

(1) 两边开方,得2(x - 1) = 3(x - 5)或2(x - 1) = -3(x - 5), 分别得x = 13和x = 17/5 (2) 只好套公式: x = (7 ± √41)/2 (3) (x - 2)(x + 1) = 0 x = 2, x = -1

(1)两边除以2,得,x2-52x+12=0,?x2-52x+(54)2-(54)2+12=0,∴(x-54)2=25?842,解得x1=5+174,x2=5?174.(2)(x+5)(16x+16×5-8)=0,x+5=0或16x+80-8=0,解得x1=-5,x2=-4.5.

(1)方程两边都乘(x-3)(x-1),得(x-5)(x-1)-(x+1)(x-3)=0,解得x=2.检验:当x=2时,(x-3)(x-1)≠0.∴x=2是原方程的解.(2)方程两边都乘(x+2)(x-2),得(x-2) 2 -(x+2)(x-2)=8,解得:x=0.检验:当x=0时,(x+2)...

因题干不全,条件不足,无法解答。

解下列方程7xチ0ナ5-4x-1=0,(x+6)(x-3)=2x-6 解: 7x²-4x-1=0 x=[4±√(16+28)]/14 =(4±√44)/14 =(4±2√11)/14 =(2±√11)/7 (x+6)(x-3)=2x-6 x²+3x-18=2x-6 x²+x-12=0 (x-3)(x+4)=0 所以x-3=0或x+4=0 所以x=3或x=-4

(1)去括号得:4x+2=x+7,移项、合并同类项得:3x=5,系数化为1得x=53;(2)去分母得:4×2x-3(3x-2)=24,去括号得8x-9x+6=24,移项、合并同类项得:-x=18,系数化为1得:x=-18.

1. x^2+10x+16=0 x^2+2*5x+25-25=16=0 (x+5)^2=9 x+5=±3 x1=-2 x2=-8 2. x^2-x-3/4=0 x^2-2*1/2x+1/4-1/4-3/4=0 (x-1/2)^2=1 x-1/2=± 1 x1=3/2 x2=-1/2

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