Question

chung minh 81^7-27^9-9^13 chia het 45

Answer 1

Ta có:81⁷-27⁹-9¹³=3²⁸-3²⁷-3²⁶=3²⁶.3²-3²⁶.3+3²⁶=3²⁶.(3²-3-1)=3²⁶.5=3²⁴.3².5=3²⁴.45 chia hết cho 45

=>đpcm

Answer 2

\(81^7-27^9-9^{13}=3^{28}-3^{27}-3^{26}=3^{24}.\left(3^4-3^3-3^2\right)=3^{24}.45\)

Chia hết cho 45 

Answer 3

81^7-27^9-9^13

=(3^4)^7-(3^3)-(3^2)^13

=3^28-3^27-3^26

=3^26(3^1-3^1-3^0)

=3^24.9.5=3^24.45 chia hết cho 45(dpcm)

Answer 4

= (3⁴)⁷-(3³)⁹-(3²)¹³=3²⁸-3²⁷-3²⁶=3²⁶(3²-3-1)=3²⁶.5=3²⁴.9.5=3²⁴.45 chia hết cho 45

Answer 5

81⁷-27⁹-9¹³=(3⁴)⁷-(3³)⁹-(3²)¹³=3²⁸-3²⁷-3²⁶=3²⁴.(3⁴-3³-3²)=3²⁴.45 chia hết cho 45

=>điều phải chứng minh