Question

Tìm chữ số tận cùng của :

a, 1023¹⁰²⁴

b, 8¹⁹⁷⁵

c, 2⁴ⁿ - 5

d, 2^{4n + 2}  + 1

Answer 1

\(1023^{1024}=\left(1023^4\right)^{256}=\left(....1\right)^{256}=\left(.....6\right)\)

\(8^{1975}=8^3.8^{1972}=512.\left(8^4\right)^{493}=512.\left(4096\right)^{493}=512.\left(.....6\right)=\left(.....2\right)\)

\(2^{4n-5}=\left(2^4\right)^n:2^5=\left(16\right)^n:32=\left(....6\right):32=\left(....8\right)\)

\(2^{4n+2}+1=\left(2^4\right)^5.2^2+1=\left(16\right)^5.4+1=\left(....6\right).4+1=\left(...4\right)+1=\left(.....5\right)\)

P/s: Hoq chắc ạ :))))