解分式方程(初二)(1)(2x²+1)\(x+2)=2x (2)(x-2)\(x+2)-1=3\(x²-4)(3) 3\(x-2 )+x\(2-x) = -2
问题描述:
解分式方程(初二)
(1)(2x²+1)\(x+2)=2x
(2)(x-2)\(x+2)-1=3\(x²-4)
(3) 3\(x-2 )+x\(2-x) = -2
答
1.去分母,2x^2+1=2x(x+2),2x^2+1=2x^2+4x,4x=1,x=1/4,经检验,x=1/4是原分式方程的根
2.去分母,(x-2)^2-(x^2-4)=3,x^2-4x+4-x^2+4=3,-4x=3-8,-4x=-5,x=4/5,经检验x=4/5是原分式方程的根
3.去分母,3-x=-2(x-2),3-x=-2x+4,2x-x=4-3,x=1,经检验x=1是原分式方程的根
答
一
(2x²+1)\(x+2)=2x
(2x²+1)\(x+2)-2x=0
(2x²+1)\(x+2)-2x (x+2)\ (x+2)=0
(2x²+1-2x²-4x)/(x+2)=0
(1-4x)/(x+2)=0
1-4x=0
x=1/4
二
(x-2)\(x+2)-1=3\(x²-4)
((x-2)(x-2))/((x+2)(x-2))-1=3/(x²-4)
(x²-4x+4)/(x²-4)-1=3/(x²-4)
(x²-4x+4)-(x²-4)=3
x²-4x+4-x²+4=3
-4x+8=3
-4x=-5
x=5/4
三
3\(x-2 )+x\(2-x) = -2
3/(x-2)+x/-(x-2)=-2
3/(x-2)-x/(x-2)=-2
(3-x)/(x-2)=-2
3-x=-2(x-2)
3-x=-2x+4
x=1