Question

[Phan Thị Thu Ngọc]

Tính nhanh

a)  (2^78+2^79+2^80) : (2^77+2^76+2^75)

b)  (5^56+5^7) : (5^49+1)

Answer 1

[Trần Đức Thắng]

\(a;\frac{2^{78}+2^{79}+2^{80}}{2^{77}+2^{76}+2^{75}}=\frac{2^{78}\left(1+2+2^2\right)}{2^{75}\left(1+2+2^2\right)}=2^3=8\)

b) \(\frac{5^{56}+5^7}{5^{49}+1}=\frac{5^7\left(5^{49}+1\right)}{5^{49}+1}=5^7\)