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解方程 x%7x69=5x1.2x

X-7×69=5×1.2X X-483=6X 6X-X=-483 5X=-483 X=-483÷5 X=-96.6

(1)移项,得5x-7x=-3-9,合并同类项,得-2x=-12,系数化为1,得x=6;(2)去括号,得3x+9-2x+2=2,移项,得3x-2x=2-9-2,合并同类项,得x=-9;(3)去分母,得2(2x+1)-(5x-1)=6,去括号,得4x+2-5x+1=6,移项合并,得-x=3,化系数为1,得x...

(1)x(3+5x)=0,∴x1=0,x2=-?35;(2)(3-x)(7x+4)=0,∴x1=3,x2=-47;(3)去分母整理得4x2-16x+12=0,即x2-4x+3=0,(x-3)(x+1)=0,∴x1=3,x2=-1,经检验x1=3,x2=-1是原方程的根.所以原方程的根为x1=3,x2=-1.

(1)2x^2+x-1=0 (x+1)(2x-1)=0 x=-1或x=1/2 (2)2x^2=5x-2 2x^2-5x+2=0 (x-2)(2x-1)=0 x=2或x=1/2 (5)3x^2-5x+2=0 (x-2)(3x-1)=0 x=2或x=1/3 3和4不能用配方法啊

1/(x^2+x)+1/(x^2+3x+2)+1/(x^2+5x+6)+1/(x^2+7x+12)+1/(x^2+9x+20) =1/x(x+1)+ 1/(x+1)(x+2) + 1/(x+2)(x+3)+ 1/(x+3)(x+4)+ 1/(x+4)(x+5) =[1/x - 1/(x+1)]+[1/(x+1) - 1/(x+2)]+[1/(x+2) - 1/(x+3)]+[1/(x+3) - 1/(x+4)]+[1/(x+4) - 1/...

(1)原式=x2?2xx?3×x?3x=x-2,当x=7+1时,原式=7+1-2=7-1≈1.65;(2)方程两边同乘以x(x-1),可得2x?x+5x-7=x2-x,解这个方程得x1=1,x2=-7,检验:把x=1代入x(x-1)中得1×(1-1)=0,故x=1不是方程的解;把x=-7代入x(x-1)中得-7×(-7-1)...

5-5分之x+1=x,x+1是整体; 25-(x+1)=5x 25-x-1=5x 25-1=5x+x 6x=24 x=4 2分之x-2(x-2是整体)-3x=-2; x-2-6x=-12 x-6x=-12+2 -5x=-10 x=2 7分之2x+1(2x+1是整体)=14分之x-5(x-5是整体)-1; 2(2x+1)=x-5-14 4x-x=-5-14-2 3x=-21 x=-7 2分之x+1...

解:1/5x+500=40%x 1/5x+500=2/5x 2/5x-1/5x=500 1/5x=500 x=500*5 x=2500

x1=-1 x2=1 x3=-1 x4=1 x5=-1

解:x-5x1/2=3.5-x 2x=3.5+5/2 2x=3.5+2.5 2x=6 x=3提交回答

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