Hướng dẫn trả lời:
Bài 10:
a) `5.125.625.`
`= 5.5^{3}.5^{4}.`
`= 5^{1+3+4}.`
`= 5^{8}.`
b) `10.100.1000.`
`= 10.10^{2}.10^{3}.`
`= 10^{1 + 2 + 3}.`
`= 10^6.`
c) `8^{4}.16^{5}.32.`
`= (2^{3})^{4}.(2^{4})^{5}.2^{5}.`
`= 2^{12}.2^{20}.2^{5}.`
`= 2^{12 + 20 + 5}.`
`= 2^{37}.`
d) `27^{4}.81^{10}.`
`= (3^{3})^{4}.(3^{4})^{10}.`
`= 3^{12}.3^{40}.`
`= 3^{12 + 40}.`
`= 3^{52}.`
Bài 11:
e) Ta có: `7.2^{13}.`
`= 7/2^{3}.2^{3}.2^{13}.`
`= 7/8 .2^{16}.`
Vì `7/8 < 1` nên `7/8 .2^{16} < 2^{16}`.
Hay `7.2^{13} < 2^{16}.`
Vậy `7.2^{13} < 2^{16}.`
f) Ta có: `27^{5}.49^{8}.`
`= (3^{3})^{5}.(7^{2})^{8}.`
`= 3^{15}.7^{16}.`
`= 3^{15}.7^{15}.7.`
`= (3.7)^{15}.7.`
`= 21^{15}.7.`
Vì `1 < 7` nên `21^{15} < 21^{15}.7.`
Hay `21^{15} < 27^{5}.49^{8}.`
Vậy `21^{15} < 27^{5}.49^{8}.`
Đáp án:
Bài 10:
a) `= 5^{8}.`
b) `= 10^{6}.`
c) `= 2^{37}.`
d) `= 3^{52}.`
Bài 11:
e) `7.2^{13} < 2^{16}.`
f) `21^{15} < 27^{5}.49^{8}.`