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[TEX]2 C_5^k+5 C_n^{k+1}+4 C_n^{k+2}+ C_n^{k+3}= C_{n+2}^{k+2}+ C_{n+3}^{k+3}[/TEX]
m.n giúp mình nha . Thanks
[TEX]2 C_5^k+5 C_n^{k+1}+4 C_n^{k+2}+ C_n^{k+3}= C_{n+2}^{k+2}+ C_{n+3}^{k+3}[/TEX]
m.n giúp mình nha . Thanks