Đối với hàng hóa công mà chi phí biên để cung cấp bằng 0 hoặc không đăng kể thì hàng hỏa cũng

DRt = \({\left( {1 + r} \right)^t}\)

DRt = \({\left( {1 + r} \right)^{ - t}}\)

DRt = \({\left( {1 - r} \right)^t}\)

DRt = \({\left( {1 - r} \right)^{ - t}}\)

\( \approx \;\)0,31 USD

\(\; \approx \) 0,69 USD

PDV = \(\mathop \sum \limits_{i = 0}^n \frac{{{R_i}}}{{{{\left( {1 + r} \right)}^i}}}\) = R₀ + \(\frac{{{R_1}}}{{\left( {1 + r} \right)}}\) + \(\frac{{{R_2}}}{{{{\left( {1 + r} \right)}^2}}}\) +……..+ \(\frac{{{R_n}}}{{{{\left( {1 + n} \right)}^n}}}\)

PDV = \(\mathop \sum \limits_{i = 0}^n \frac{{{R_i}}}{{{{\left( {1 + r} \right)}^i}}}\) = R₀ - \(\frac{{{R_1}}}{{\left( {1 + r} \right)}}\) + \(\frac{{{R_2}}}{{{{\left( {1 + r} \right)}^2}}}\) +……..+ \(\frac{{{R_n}}}{{{{\left( {1 + n} \right)}^n}}}\)

PDV = \(\mathop \sum \limits_{i = 0}^n \frac{{{R_i}}}{{{{\left( {1 + r} \right)}^i}}}\) = \(\frac{{{R_0}}}{{\left( {1 + r} \right)}}\) + \(\frac{{{R_2}}}{{{{\left( {1 + r} \right)}^2}}}\) +……..+ \(\frac{{{R_n}}}{{{{\left( {1 + n} \right)}^n}}}\)

PDV = \(\mathop \sum \limits_{i = 0}^n \frac{{{R_i}}}{{{{\left( {1 + r} \right)}^i}}}\) = R₀ + \(\frac{{{R_1}}}{{\left( {1 - r} \right)}}\) + \(\frac{{{R_2}}}{{{{\left( {1 - r} \right)}^2}}}\) +……..+ \(\frac{{{R_n}}}{{{{\left( {1 - n} \right)}^n}}}\)