1Tính \(\left(\frac{-7}{11}\right)^{38}\)* \(\left(\frac{-11}{7}\right)^{39}\)
2 Tìm x biết
b)\(\frac{x+1}{8}=\frac{8}{x+1}\) c) \(\left(1,78^2^{\cdot x-2}-1,78^x\right)\div1,78^x=0\) d) \(|2x+1|+|x|=x\)
3) Chứng minh rằng
a) \(27^8-3^{21}\)chia hết cho 26 b) \(5^{19}+5^{18}+5^{17}\)chia hết cho 31
c) \(81^7-27^9-9^{13}\)chia hết cho 45 d)\(8^{12}-2^{^{33}}-2^{30}\)chia hết cho 55