chứng minh rằng a, 5^5 – 5^4 + 5^3 : 7 b, 10^6 – 5^7 : 59 c, 81^7 – 27^9 – 9^13 : 45 30/07/2021 Bởi Katherine chứng minh rằng a, 5^5 – 5^4 + 5^3 : 7 b, 10^6 – 5^7 : 59 c, 81^7 – 27^9 – 9^13 : 45
Giải thích các bước giải: a, $5^{5}-5^{4}+5^{3}$$= 5^{3}\left ( 5^{2}-5+1 \right )$$= 5^{3}.21\vdots 7$ b, $10^{6}-5^{7}$$= 2^{6}.5^{6}-5^{7}$$= 5^{6}\left ( 2^{6}-5 \right )$$= 5^{6}\left ( 64-5 \right )$$= 5^{6}.59\vdots 59$ c, $81^{7}-27^{9}-9^{13}$$= 3^{28}-3^{27}-3^{26}$$= 3^{24}\left ( 3^{4}-3^{3}-3^{2} \right )$$= 3^{24}.45\vdots 45$ Bình luận
Giải thích các bước giải:
a,
$5^{5}-5^{4}+5^{3}$
$= 5^{3}\left ( 5^{2}-5+1 \right )$
$= 5^{3}.21\vdots 7$
b,
$10^{6}-5^{7}$
$= 2^{6}.5^{6}-5^{7}$
$= 5^{6}\left ( 2^{6}-5 \right )$
$= 5^{6}\left ( 64-5 \right )$
$= 5^{6}.59\vdots 59$
c,
$81^{7}-27^{9}-9^{13}$
$= 3^{28}-3^{27}-3^{26}$
$= 3^{24}\left ( 3^{4}-3^{3}-3^{2} \right )$
$= 3^{24}.45\vdots 45$