(-y²/3x)³÷6x²y^7÷(-1/9x²y)²
=-y^6/3x³÷6x²y^7÷1/81x^4y²
=-1/18x^5y÷1/81x^4y²
=-9/2x^9y^3
如追加其它问题,采纳本题后点击想我求助,