SOLUTION: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers. {{{ N= (x^2-3x)/(2) }}} solve for x (number of diagonals of polygon with

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers. {{{ N= (x^2-3x)/(2) }}} solve for x (number of diagonals of polygon with      Log On


   

Question 367304: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers.
+N=+%28x%5E2-3x%29%2F%282%29+ solve for x
(number of diagonals of polygon with x sides)
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
Ureka!
n=(x^2-3x)/(2)
x^2-3x=2n
x^2-3x+ 9/4=2n + 9/4 Completing the square.
(x - 3/2)^2 = 2n + 9/4
x - 3/2 = +-sqrt(2n + 9/4)
x=3/2 +- sqrt((8n+9)/4)
=3/2 +- sqrt(8n-9)/2
x=(3+sqrt(8n-9))/2, x=(3-sqrt(8n-9))/2
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Ed