Question

[Quách Trung Kiên]

Cho a, \(\frac{a}{b}\)=\(\frac{b}{d}\)CM \(\frac{a^2+b^2}{b^2+d^2}\)=\(\frac{a}{b}\)

       b, \(\frac{a}{b}\)=\(\frac{c}{d}\)CM \(\frac{a^2+b^2}{c^2+d^2}\)=\(\frac{ab}{cd}\)

       c, a₂² = a₁.a₃ ; a₃²=a₂.a₄,....,a₂₀₁₀²=a₂₀₀₅.a₂₀₁₁

                    _{CM \(\frac{a_1^{2010}+a_2^{2010}+a_3^{2010}+....+a^{2010}_{2010}}{a_2^{2010}+a_3^{2010}+a_4^{2010}+....+a^{2010}_{2011}}=\frac{a_1}{a_{2011}}\)}