Question

Good evening,

My doubt is

The square of a positive integer CANNOT be of the form (k is an integer):

(a) 3k + 1 (b) 4k + 2 (c) 5k + 1 (d) 5k + 4

Answer 1

In the case of 3k+1
when k=1
3*1+1=4
Which is the sqare of 2
In the case of 5k+1
When k=3
5*3+1=16
Which is the sqare of 4
In the case of 5k+4
When k=1
5*1+4=9
Which is the sqare of 3
But in the case of 4k+2
For any value of k we can not get a perfect sqare
So 4k+2 is the answer