Answer:
x = 50 , side length = 2640
Step-by-step explanation:
the sides of a regular polygon are equal, then
x² + 2x + 40 = x² - x + 190 ( subtract x² from both sides )
2x + 40 = - x + 190 ( add x to both sides )
3x + 40 = 190 ( subtract 40 from both sides )
3x = 150 ( divide both sides by 3 )
x = 50
substitute x = 50 into either of the 2 given expressions for side length
x² + 2x + 40 = 50² + 2(50) + 40 = 2500 + 100 + 40 = 2640
