Question

If (30k)2 = 3600, then which of the following cannot
be triangular number?
(1) 4+k
(2) 5-k
(3) 2k + 1
(4) 2k-3
Which option will it be?​

Answer 1

Answer:(30k)2=3600

30k=60

K=2

2k+1=5 and 5 is not a triangular number

So the answer isoption(3)

Step-by-step explanation:

Answer 2

if (30k)² = 3600 Then 2k + 1 cannot be triangular number

Step-by-step explanation:

(30k)² = 3600

Taking Square root both sides

=> 30k = ± 60

=> k = ± 2

Triangular numbers are  1 , 3 ,  6  , 10  , 15  and so on

4+k  =  6 or 2    ( 6 is a triangular number)

5 - k  = 3  or 7    ( 3 is  a Triangular number)

2k + 1  = 5  , -3

2k - 3 = 1   , -7    (1  is a triangular Number)

Hence 2k + 1  cannot be triangular number