Question

[Nhok]

1/ Chứng minh

a)7^6 + 7^5 - 7^4 chia hết 55

b)16^5 + 2^5 chia hết 33

c)81^7 - 27^9 - 9^13 chia hết 405

2/ Tìm x

a)5^x + 5^x+2 = 650

b)3^x+1 + 5 x 3^x+1 = 162

Giải giúp mình nha mn

Answer 1

[zZz Cool Kid_new zZz]

\(7^6+7^5-7^4\)

\(=7^4\left(7^2+7-1\right)\)

\(=7^4\cdot55⋮55\)

Answer 2

[zZz Cool Kid_new zZz]

\(16^5+2^5\)

\(=\left(2^4\right)^5+2^5\)

\(=2^{20}+2^5\)

\(=2^5\left(2^{15}+1\right)\)

\(=2^5\cdot32769⋮33\)