2的平方根是 ±根号2-2的平方根是 ±i根号2 （i是虚数单位,i=根号-1）所以 x+2 = (±根号2)^3 = ±2^(3/2) 或 (±i根号2)^3 = ±i^3 2^(3/2) = 负正 i 2^(3/2)x = ±2^(3/2) - 2 或 ±i2^(3/2) - 22x+y+7的立方根是3...