Solve for n: 119 = n^2 - 3n / 2

[get_rekd]

d=n^2 - 3n / 2

where d = number of diagonals
and n = the number of sides of the polygon.

A polygon has 119 diagonals, how many sides does it have?

119 = n^2 - 3n / 2

I am not sure how to do this? can someone please help?

sorry this isn't physics related

I know I need to use the quadratic formula, but how?

 

[rl.bhat]

d=n^2 - 3n / 2 this should be d = ( n^2 - 3n)/2
Wright the given equation 119 = n^2 - 3n / 2 as 2*119 = n^2 - 3n and solve the quadritic equation to get the value of n.

 

[get_rekd]

thank you very much