So sánh : M = 17 mũ 20 + 1 phần 17 mũ 19 + 1 N = 17 mũ 17 + a phần 17 mũ 16 + 1

Giải thích các bước giải:

Ta có: 

$17^{20}+1>17^{19}+1$

$\to \dfrac{ 17^{20}+1}{17^{19}+1}>1$

$\to \dfrac{ 17^{20}+1}{17^{19}+1}>\dfrac{ 17^{20}+1+17^3-1}{17^{19}+1+17^3-1}$

$\to \dfrac{ 17^{20}+1}{17^{19}+1}>\dfrac{ 17^{20}+17^3}{17^{19}+17^3}$

$\to \dfrac{ 17^{20}+1}{17^{19}+1}>\dfrac{ 17^3(17^{17}+1)}{17^3(17^{16}+1)}$

$\to \dfrac{ 17^{20}+1}{17^{19}+1}>\dfrac{17^{17}+1}{17^{16}+1}$

$\to M>N$