先化简再求值:-3(2x-y)-{7-〔6x+2y-(10x-8y)〕+x-2(3x-4y)}已知x=-1/5,y=-5
先化简再求值:-3(2x-y)-{7-〔6x+2y-(10x-8y)〕+x-2(3x-4y)}已知x=-1/5,y=-5
数学人气:662 ℃时间:2019-08-18 00:06:20
优质解答
-3(2x-y)-{7-〔6x+2y-(10x-8y)〕+x-2(3x-4y)}=-6x+3y-{7-[6x+2y-10x+8y]+x-6x+8y}=-6x+3y-{7-6x-2y+10x-8y+x-6x+8y}=-6x+3y-{7-x-2y}=-6x+3y-7+x+2y=-5x+5y-7=-5*(-1/5)-5*(-5)-7=1+25-7=19
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