1、（-2xy的n+1次方）²（-3xn+1次方y²）³
=(4x²y的2n+2次方)(-27x的3n+3次方y的6次方)
=-108x的3n+5次方y的2n+8次方
2、(25x²+15x³y-20x的4次方)÷(-5x²)
=-5-3xy+4x²