Question

Which of the following is a triangular number? (9, 7, 11, 15 )​

Answer 1

Answer:

15 is right answer.

hope it'll help you....m

Answer 2

Answer:

15 is triangular number

Step-by-step explanation:

because in 9, 7, 11 and 15, 15 is the submition of the natural number which are 1+2+3+4+5=15