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Let $r$ be the positive real solution to $x^3 + \frac{2}{5} x - 1 = 0.$ Find the exact numerical value of $r^2 + 2r^5 + 3r^8 + 4r^{11} + \dotsb.$

NewMember Jan 5, 2020

ThatOnePerson · Answer 1 · 2020-01-05T02:10:19

Why do you need help ASAP? Is this a homework question, or a test question, or something serious? If so, then we shouldn't answer it.