81^7-27^9-9^13
=(3^4)^7-(3^3)^9-(3^2)^13
=3^28-3^27-3^26
=3^26.3^2-3^26.3-3^26
=3^26.(3^2-3-1)=3^26.5=3^22.3^4.5=3^22.405 luôn chia hết cho 405
( 817 - 279 - 913 ) chia hết cho 405 ấn vào dòng chữ màu xanh nhé
81^7-27^9-9^13
=(3^4)^7-(3^3)^9-(3^2)^13
=3^28-3^27-3^26
=(3^26.3^2)-(3^26.3^1)-(3^26.1)
=3^26.(9-3-1)
=3^22.(3^4.5)
=3^22.405 chia hết cho 405
=> 81^7-27^9-9^13 chia hết cho 405
\(81^7-27^9-9^{13}=3^{28}-3^{27}-3^{26}\)
\(=3^{22}.\left(3^6-3^5-3^4\right)=3^{22}.405\)
=> ĐPCM
817-279-913
= (34)7-(33)9-(32)13
= 328-327-326
= 326(32-3-1)
= 326.5
= 322.34.5
= 322.405 chia hết cho 405
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