有有理根则sjx是平方式
所以(n+1)²+8(3n²-4n+m)
=n²+2n+1+24n²-32n+8m
=25n²-30n+8m+1
=25n²-30n+9+8m-8
=(5n-3)²+8m-8是平方式
所以8m-8=0
m=1