We are to divide n^2 - 8 by 33 and find the possible remainder which could be between 0,15 and 21
Lets keep the remainder as r
=>n^2 - 8 = 33k + r where k is some integer
=> n^2 = 33k + (r + 8)
1 -> Check for remainder 0n^2 = 33k + 8
=> We divide both sides by 3, since 33 is a multiple of 3, we can start of by checking with 3
=> 33k + 8 upon division by 3 would leave a remainder of 2
=> n^2 would also have to leave a remainder of 2
Now we know that, among the possibilities an integer here should be a multiple of 3, or 1 more than a multiple of 3 or 1 less than a multiple of 3
=> Their squares are
(3m)^2 = 9m^2 which leaves remainder of 0
(3m+1)^2 = 9m^2 + 6m + 1 which leaves a remainder of 1
(3m+2)^2 = 9m^2 + 12m + 4 which also leaves a remainder of 1
=> Perfect square only has 0 or 1 as remainder when divided by 3
=> 0 cant be remainder
2-> Remainder = 15n^2 = 33k + 23
Upon dividing by 3 similarly as above,
We see 23 leaves remainder 2 upon division by 3
=> n^2 would also need remainder 2
We will again see the same thing occur
=> Remainder 15 is not possible
3-> Remainder = 21n^2 = 33k +29
We see 29 leaves remainder 2 upon division by 3
=> n^2 would also need to leave remainder 2
Therefore we see the same thing as above
=> Remainder 21 is not possible
=> E. None of these