Đáp án: `+` Giải thích các bước giải:

 `B = \frac{25^6 + 5^4}{25^4 + 25}`

`B = \frac{(5^2)^6 + 5^4}{(5^2)^4 + 5^2}`

`B = \frac{5^{12} + 5^4}{5^8 + 5^2}`

`B = \frac{5^4(5^8 + 1)}{5^2(5^6 + 1)}`

`B = 5^2 \cdot \frac{5^8 + 1}{5^6 + 1}`

`B = 25 \cdot \frac{5^8 + 1}{5^6 + 1}`

`E = \frac{8^{10} + 4^{10}}{8^4 + 4^{11}}`

`E = \frac{(2^3)^{10} + (2^2)^{10}}{(2^3)^4 + (2^2)^{11}}`

`E = \frac{2^{30} + 2^{20}}{2^{12} + 2^{22}}`

`E = \frac{2^{20}(2^{10} + 1)}{2^{12}(1 + 2^{10})}`

`E = \frac{2^{20}}{2^{12}}`

`E = 2^8`

`E = 256`