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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Có phải đề như thế này đúng không
\(\frac{5^2.6^{11}.16^2+6^2.12^6.15^2}{2.6^{12}.10^4-81^2.960^3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(\frac{5^2.6^{11}.16^2.6^2.12^6.15^2}{2.6^{12}.10^4-81^2.960^3}\) = \(\frac{5^2.6^{11}.6^2.6^2.6^6.2^6.3^2.5^2}{2.2^{12}.3^{12}.2^4.5^4-3^8.2^{15}.3^3}\) = \(\frac{5^6.6^{21}.2^8.3^2}{2^{17}.3^{12}.5^4-3^{11}.2^{15}}\) = \(\frac{5^6.3^{23}.2^{29}}{3^{11}.2^{15}.\left(2^2.3.5^4-1\right)}\)
= \(\frac{5^6.3^{13}.2^{14}}{2^2.3.5^4-1}\)
Nhớ cho mk nha bạn!
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a) \(\frac{5^2.6^{11}.16^2+6^2.11^6.15^2}{2.6^{12}.10^{14}-81^2.960^3}=\frac{5^2.2^{19}.3^{11}+2^2.3^4.11^6.5^2}{2^{27}.3^{12}.5^{14}-3^{11}.2^{18}.5^3}\)
\(=\frac{5^2.2^2.3^4.\left(2^{17}.3^7+11^6\right)}{2^{18}.3^{11}.5^3.\left(2^9.3.5^{11}-1\right)}=\frac{2^{17}.3^7+11^6}{2^{16}.3^7.5.\left(2^9.3.5^{11}-1\right)}\)
b) Đặt A = 2528 + 2524 +....+ 254 +1
=> 254.A = 2532 + 2528 +...+ 258 + 254
=> 254.A - A = 2532 -1
\(A=\frac{25^{32}-1}{25^4-1}\)
tương tự....
Thay vào:
\(\frac{25^{28}+25^{24}+...+25^4+1}{25^{30}+25^{28}+...+25^2+1}=\frac{\frac{25^{32}-1}{25^4-1}}{\frac{25^{32}-1}{25^2-1}}=\frac{25^2-1}{25^4-1}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)