Question

Chứng minh:

a) 7^{6 +} 7^{5 -} 74 chia hết 55

b) 16⁵ + 2¹⁵ chia hết 33

c) 81⁷ - 27^{9 -} 9¹³ chia hết 405

Answer 1

7 mũ 4 phải ko bn

 

Answer 2

7^4.(7^2+7-1)=7^4 :55 chia hết cho 55

Answer 3

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 het cho 405
=> 81^7-27^9-9^13 chia het cho 405
 

Answer 4

tick cho mk nha

Answer 5

 Ta có: 16^5=2^20 
=> A=16^5 + 2^15 = 2^20 + 2^15 
= 2^15.2^5 + 2^15 
= 2^15(2^5+1) 
=2^15.33

=> chia hết cho 33