3m-4与7-4m是N的平方根∴3m-4+7-4m=0m=3∴N=25-2-N=-27-2-N的立方根=-3
N=25-2-N的立方根=-3
3m-4 = 7-4m7m=11 m = 11/73m-4 = √N33/7 - 4 =√N5/7 =√NN = 25/49-2-N的立方根 = (-2 - 25/49) ^(1/3)= (-123/49) ^(1/3)
