Question

合并同类项，化简求值题

3×2-2{x-5[x-3(x-2×2)-3(x2-2x)]-(x-1)},其中，x=2合并同类项，化简求值

Answer 1

3×2-2{x-5[x-3(x-2×2)-3(x2-2x)]-(x-1)}=6-2{x-5[x-3x+12-3x^2+6x]-x+1}=6-2{x-60-20x+15x^2-x+1}=6-30x^2+40x+118=-30x^2+40x+124当x=2时原式=-30×4+40×2+124=84

Answer 2

3×2-2{x-5[x-3(x-2×2)-3(x2-2x)]-(x-1)}=6-2{x-5[x-3x+12-3x2+6x]-x+1}=6-2{5x+15x-60+15x2-30x-x+1}=6-10x-30x+120-30x2+60x+2x-2=-30x2+22x+64x=2时-30x2+22x+64=-120+44+64=-12