Question

先化简,再求值:3x²-｛5x²-【2x-（3x²-3x+x²）】+5x｝,其中？

Answer 1

3x²-｛5x²-【2x-（3x²-3x+x²）】+5x｝
=3x²-5x²+【2x-（3x²-3x+x²）】-5x
=3x²喊携-5x²+2x-（3x²-3x+x²）-5x
=3x²-5x²+2x-3x²+3x+x²--5x
=-6x²握卜
x=二分之一时
原式＝－3/2,8,化简结果是-6x^2，带进去就好了得-3/2,2,原段渗穗式
=3x²-｛5x²-【2x-（4x²-3x）】+5x｝
=3x²-[5x²-(2x-4x²+3x)+5x]
=3x²-[5x²-(5x-4x²)+5x]
=3x²-[(5x²-5x+4x²)+5x]
=3x²-9x²
=-6x²
=-6×(1/2)²
=-3/2,0,先化简,再求值:3x²-｛5x²-【2x-（3x²-3x+x²）】+5x｝,其中x=二分之一