Cho $b^{2}$ = ac ; $c^{2}$ = bd CMR : $\frac{a^{3}+b^{3}+c^{3}}{b^{3}+c^{3}+d^{3}}$ = ($\frac{a+b+c}{b+c+d}$)^3

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1. Giải thích các bước giải:

   $b^2=ac\rightarrow \dfrac{a}{b}=\dfrac{b}{c}$

   $c^2=bd\rightarrow \dfrac{b}{c}=\dfrac{c}{d}$

   $\rightarrow \dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{d}=\dfrac{a+b+c}{b+c+d}$ 

   $\rightarrow \dfrac{a^3}{b^3}=\dfrac{b^3}{c^3}=\dfrac{c^3}{d^3}=\dfrac{(a+b+c)^3}{(b+c+d)^3}=\dfrac{a^3+b^3+c^3}{b^3+c^3+d^3}$ 

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