Question

the fourth power of any in integer is either of the form 5k or 5k+1 ​

Answer 1

Answer:

Any number with either 1 or 6 in the unit's place can be expressed as 5k+1, where k is some integer. So, the fourth power of a number can be expressed in the form 5k+1 for all integers except those which are multiples of 5, in which case they can be expressed in the form 5k.