Đáp án + Giải thích các bước giải :

`1.`

`a) 2^100 = 2^(4×25) = (...6)`

`b) 3^200 = 3^(4×50) = (...1)`

`c) 4^500 = 2^1000 = 2^(4×250) = (...6)`

`d) 7^150 = 7^(4×37+2) = 7^(4×37) × 7^2 = (...1) × (...9) = (...9)`

`e) 8^250 = 8^(4×62+2) = 8^(4×62) × 8^2 = (...6) × (...4) = (...4)`

`g) 9^200 = 9^(2×100) = (...1)`

`2.`

`a) 2^300 + 3^200 = 2×(4×75) + 3^(4×50) = (...6) + (...1) = (...7)`

`b) 14^200 + 15^12345 = 14^(2×100) + (...5) = (...6) `

`c) 3^500 + 3^70000 = 3^(4×125) + (...6) = (...1) + (...6) = (...7)`

`d) 8^900 + 9^800 = 8^(4×225) + 9^(2×400) = (...6) + (...1) = (...7)`

`3.`

`a) 5^200 - 3^100 `

` = (...5) - 3^(4×25)`

` = (...5) - (...1) `

` = (...4)`

`b) 7^150 - 2^150 `

` = 7^(4×37+2) - 2^(4×37+2)`

` =(...1) × (...9) - (...6) × (...4)`

` =(...9) - (...4)`

` = (...5)`

`c) 13^70 - 7^80 `

` = 13^(4×17+2) - 7^(4×20)`

` = (...6) × (...9) - (...1)`

` = (...4) - (...1)`

` = (...3)`

`d) 20^70 - 15^30 `

` = (...0) - (...5)`

` = (...5)`

`4.`

`a) 15^300 × 17^200 = (...5) × 17^(4×50) = (...5) × (...1) = (...5)`

`b) 15^7 × 16^8 × 11^500 = (...5) × (...6) × (...1) = (...0)`

`color{White}{***ilovemath}`