化简求值:(x-1/2x-1)(x-1/2x+1)-(x-1/2x-1)^2 其中x=1.7,y=3.9

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化简求值:(x-1/2x-1)(x-1/2x+1)-(x-1/2x-1)^2 其中x=1.7,y=3.9

化简求值:(x-1/2x-1)(x-1/2x+1)-(x-1/2x-1)^2 其中x=1.7,y=3.9
化简求值:(x-1/2x-1)(x-1/2x+1)-(x-1/2x-1)^2 其中x=1.7,y=3.9

化简求值:(x-1/2x-1)(x-1/2x+1)-(x-1/2x-1)^2 其中x=1.7,y=3.9
[(x-1)/(2x-1)][(x-1)/(2x+1)]-[(x-1)/(2x-1)]²
=(x-1)²/[(2x-1)(2x+1)]-(x-1)²/(2x-1)²
=[(x-1)²/(2x-1)][1/(2x+1)-1/(2x-1)]
=[(x-1)²/(2x-1)][(2x-1-2x-1)/(2x+1)(2x-1)]
=[-2(x-1)²]/[(2x-1)²(2x+1)]
当x=1.7 y=3.9时,
原式=[-2×0.49]/[5.76×4.4]=-245/6336