√(x^5+x^4y²) = x² √(x+y²) √(a^5+2a³b²+ab^4) = √{a(a²+b²)² } = (a²+b²) √a √(12x²y+24x²+y³) = ?最后一题有误，如果是：√(12x²y+36x²y+y³) =√(36x²y+12x²y+y³) =√{y(6x+y)²} = |6x+y| √y
