先化简,再求值:1/2x-2(x-1/3y^2)+3(-1/2x+1/9y^2)其中x.y满足(x-2)^2+丨y+3丨=0
问题描述:
先化简,再求值:1/2x-2(x-1/3y^2)+3(-1/2x+1/9y^2)其中x.y满足(x-2)^2+丨y+3丨=0
答
∵(x-2)^2+丨y+3丨=0∴x=2,y=﹣3∴1/2x-2(x-1/3y^2)+3(-1/2x+1/9y^2)=1/2x-2x+2/3y²-3/2x+1/3y²=﹙1/2-2-3/2﹚x+﹙2/3+1/3﹚y²=﹣3x+y²=﹣3×2+﹙﹣3﹚²=﹣6+9=3...