Question

solve the following questions​

Answer 1

Step-by-step explanation:

120=n^2 + n \2

240 = n^2 + n

n^2 + n -240 = 0

n^2 +16n -15n -240= 0

n(n+16) - 15(n +16) =0

(n+16) (n-15)= 0

n cannot be -16

so the value of n= 15

( Proof by putting 15 :: 15(15+1)\2 = 120 )