(1)分析：两个非负数和为零,必须各自为零即2x-1=0,y+1=0解得：x=1/2,y=-1带入：（1/2）^2+(-1)^2=1/4-1/2=-1/4(2)分析：二次根式必须被开方数大于等于零所以,根据题意可得：x^2-4≥0且4-x^2≥0,∴x^2=4,则x=2或x=-2...