Question

Nth term of a sequence is n(n+1) what term is 240? is 55 a term in the sequence?​

Answer 1

a₁₅ = 240

55 is not term in the sequence

Explanation:

`n(n+1)=240\\\\n^2+n-240=0\\\\n=(-1\pm√(1-4(-240)))/(2)=(-1\pm√(1+960))/(2)=(-1\pm31)/(2)\quad\wedge\quad n\in N_+\\\\n=15`

if n is even number then (n+1) is odd number and if n is odd number then (n+1) is even number

The product of numbers where one of them is even will always be even.

55 is odd number so it is not term of this sequence.