原式=1/3x²+1/5x²y³-x²-5kx²y³+2
=(1/3x²-x²)+(1/5x²y³-5kx²y³)+2
=-2/3x²+(1/5-5k)x²y³+2
因为原式中不含x²y³项,所以这项的系数为0
所以有
1/5-5k=0
5k=1/5
k=1/25
原式=1/3x²+1/5x²y³-x²-5kx²y³+2
=(1/3x²-x²)+(1/5x²y³-5kx²y³)+2
=-2/3x²+(1/5-5k)x²y³+2
因为原式中不含x²y³项,所以这项的系数为0
所以有
1/5-5k=0
5k=1/5
k=1/25