He function $f$ satisfies\[f(x) + f(2x + y) + 5xy = f(3x - y) + 2x^2 + 1\]for all real numbers $x$, $y$. determine the value of $f(10)$.

Rate of return douglas keel, a financial analyst for orange industries, wishes to estimate the rate of return for two similar-risk investments, x and y. douglas's research indicates that the immediate past returns will serve as reasonable estimates of future returns. a year earlier, investment x had a market value of $27 comma 000; and investment y had a market value of $46 comma 000. during the year, investment x generated cash flow of $2 comma 025 and investment y generated cash flow of $ 6 comma 770. the current market values of investments x and y are $28 comma 582 and $46 comma 000, respectively. a. calculate the expected rate of return on investments x and y using the most recent year's data. b. assuming that the two investments are equally risky, which one should douglas recommend? why?