To solve the equation x + x^2 + x^3 + x^4... = 14, one can apply the formula for an infinite geometric series, which is valid for -1 < x < 1. This formula states that the sum can be expressed as a0 / (1 - x), allowing for the transformation of the series into a solvable equation. The discussion emphasizes the importance of using this formula correctly to find the value of x. Additionally, the thread notes that a similar question has been previously addressed, leading to its closure. The focus remains on applying the geometric series formula to derive the solution.