方程(2x-1)²-(1-3x)²=5(1-x)(x+1)的解是( ) A.x=﹣2 B.x=﹣2.5 C.x=2 D=2.5
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![方程(2x-1)²-(1-3x)²=5(1-x)(x+1)的解是( ) A.x=﹣2 B.x=﹣2.5 C.x=2 D=2.5](/uploads/image/z/387423-63-3.jpg?t=%E6%96%B9%E7%A8%8B%EF%BC%882x%EF%BC%8D1%EF%BC%89%26%23178%3B%EF%BC%8D%EF%BC%881%EF%BC%8D3x%EF%BC%89%26%23178%3B%3D5%EF%BC%881%EF%BC%8Dx%EF%BC%89%EF%BC%88x%2B1%EF%BC%89%E7%9A%84%E8%A7%A3%E6%98%AF%EF%BC%88+%EF%BC%89+A.x%3D%EF%B9%A32+B.x%3D%EF%B9%A32.5+C.x%3D2+D%3D2.5)
方程(2x-1)²-(1-3x)²=5(1-x)(x+1)的解是( ) A.x=﹣2 B.x=﹣2.5 C.x=2 D=2.5
方程(2x-1)²-(1-3x)²=5(1-x)(x+1)的解是( ) A.x=﹣2 B.x=﹣2.5 C.x=2 D=2.5
方程(2x-1)²-(1-3x)²=5(1-x)(x+1)的解是( ) A.x=﹣2 B.x=﹣2.5 C.x=2 D=2.5
(2x-1)²-(1-3x)²=5(1-x)(x+1)
[(2x-1)-(1-3x)][(2x-1)+(1-3x)]=5(1-x)(x+1)
[(2x-1)-1+3x][2x-1+1-3x]=5(1-x)(1+x)
(5x-2)(-x)=5(1-x²)
-5x²+2x=5-5x²
2x=5
x=2.5
故选D
我觉得直接代人A、B、C、D答案检验,判断等式左边是否等于右边更快!
(2x-1)²-(1-3x)²=5(1-x)(1+x)
(2x-1+1-3x)(2x-1-1+3x)=5(1-x)(1+x)
-x(5x-2)=5(1-x²)
-5x²+2x=5-5x²
2x=5
x=2.5
因此选D
4x²-4x+1-1-9x²+6x=5x+5-5x²-5x
2x=5
x=2.5
D .x=2.5
4x^2+1-4x-1-9x^2+6x=5-5x^2 2x=5 x=2.5
我也不懂
(2x-1)²-(1-3x)²=5(1-x)(x+1)
[(2x-1)-(1-3x)][(2x-1)+(1-3x)]=5(1-x)(x+1)
[(2x-1)-1+3x][2x-1+1-3x]=5(1-x)(1+x)
(5x-2)(-x)=5(1-x²)
-5x²+2x=5-5x²
2x=5
x=2.5
所以选:D