先化简再求值 5x-{2y-3x+[5x-2(y-2x)+3y]} 其中x=-1/2,y=-1/6
问题描述:
先化简再求值 5x-{2y-3x+[5x-2(y-2x)+3y]} 其中x=-1/2,y=-1/6
答
=5x-(2y-3x+x+y)
=3x+3y
=3*-1/2+3*-1/6
=-2
答
5x-{2y-3x+[5x-2(y-2x)+3y]}
=5x-2y+3x-[5x-2y+2x+3y]
=8x-2y-(7x+y)
=8x-2y-7x-y
=x-3y
将x=-1/2,y=-1/6带入上式,
x-3y
=-1/2+1/2
=0
答
5x-{2y-3x+[5x-2(y-2x)+3y]}
=5x-[2y-3x+(5x-2y+4x+3y)]
=5x-[2y-3x+(9x+y)]
=5x-(2y-3x+9x+y)
=5x-(3y+6x)
=5x-3y-6x
=-x-3y
=-(-1/2)-3*(-1/6)
=1/2+1/2
=1
答
化简结果:-x-3y,答案:1