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

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To find the number of sides of a polygon with 119 diagonals, the equation 119 = (n^2 - 3n) / 2 is used. Rearranging this gives 238 = n^2 - 3n, leading to the quadratic equation n^2 - 3n - 238 = 0. The quadratic formula can then be applied to solve for n. This process will yield the number of sides in the polygon. The discussion emphasizes the correct setup and solving of the quadratic equation.
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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?
 
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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.
 
thank you very much
 

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