Let the following be a equation define a yield curve: S_t = 0.08 + 0.003k - 0.002k^2 Let S_k stand for the annual effective rate of return for a zero coupon bond bought today with a maturity term of k. Let the following be a equation define a yield curve: S_t = 0.08 + 0.003k - 0.002k^2 Let S_k stand for the annual effective rate of return for a zero coupon bond bought today with a maturity term of k