∵x+y-4x+y+4+1/4 =(x-4x+4)+(y+y+1/4) =(x-2)+(y+1/2) =0 而要使两个非负数的和为0,那么这两个数均为0 ∴x-2=0,y+1/2=0 ∴x=2,y=-1/2 ∴原式=(-1/2)^(-2)+3×2×（-1/2） =4-3 =1