-12, I do not understand

Find the point of diminishing returns (x,y) for the function R(x) = - 0.2x3 +4.3x2 + 2x where R(x) represents revenue (in thousands of dollars) and x represents the amount spent on advertising (in thousands of dollars). The point of diminishing returns occurs at approximately . (Type an ordered pair. Do not round until the nal answer. Then round to two decimal places as needed.)