Tìm chữ số tận cùng biểu thức A=1+3mũ2+3mũ4+3mũ 6+3mũ8+...+3mũ2022 +3mũ2024
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Ta có: \(S=3+3^2+3^3+\cdots+3^{2024}\)
\(=\left(3+3^2\right)+\left(3^3+3^4+3^5\right)+\left(3^6+3^7+3^8\right)+\cdots+\left(3^{2022}+3^{2023}+3^{2024}\right)\)
\(=12+3^3\left(1+3+3^2\right)+3^6\left(1+3+3^2\right)+\cdots+3^{2022}\left(1+3+3^2\right)\)
\(=12+13\left(3^3+3^6+\cdots+3^{2022}\right)\)
=>S không chia hết cho 13
b, = \(\frac{3^9\cdot3\cdot11+15\cdot3\cdot3^8}{16\cdot3^9}\)
= \(\frac{3^9\cdot33+15\cdot3^9}{16\cdot3^9}\)
= \(\frac{3^9\cdot\left(33+15\right)}{3^9\cdot16}\)
=\(\frac{48}{16}=3\)
a, =\(\frac{\left(3\cdot4\right)^5}{4^3\cdot3^4}\)= \(\frac{3^4\cdot3\cdot4^3\cdot4^2}{4^3\cdot3^4}\)= 3 * 4^2 = 3 * 16 = 48
b, (310*11+38*45)/16*39=3^10*11+3^10*5/16*3^9=3^10*16/3^9*16=3
a, 12^5/64*3^4=2^10*3^5/2^6*3^4=2^4*3=48
S=3+3^2+3^3+...+3^2022
3S=3.(3+3^2+3^3+...+3^2022)
3S=3^2+3^3+3^4+...+3^2023
⇒3S-S=(3^2+3^3+3^4+...+3^2023)-(3+3^2+3^3+...+3^2022)
⇒2S=3^2023-3
⇒S=3^2023-3 / 2
S=3+3^2+3^3+...+3^2022
=>3S=3^2+3^3+3^4+...+3^2023
=>3S-S=(3^2+3^3+3^4+...+3^2023)-(3+3^2+3^3+...+3^2022)
=>2S=3^2023-3
=>S=\(\dfrac{3^{2023}-3}{2}\)
Vậy S=\(\dfrac{3^{2023}-3}{2}\)
Ta có:
32018 = (34)504 x 32 = (...1)504 x 9 = ...1 x9=....9
Vậy chữ số tận cùng là 9 => x=9
\(A=3^1+3^2+3^3+3^4+...+3^{199}\)
\(3A=3^2+3^3+3^4+3^5+...+3^{200}\)
\(3A-A=\left(3^2+3^3+3^4+...+3^{200}\right)-\left(3^1+3^2+3^3+...+3^{199}\right)\)
\(2A=3^{200}-3^1\)
\(A=\frac{3^{200}-3}{2}\)
=))
Đặt \(A=3^1+3^2+3^3+...+3^{199}\)
\(\Rightarrow3A=3^2+3^3+3^4+...+3^{200}\)
Lấy 3A trừ A theo vế ta có :
\(3A-A=\left(3^2+3^3+3^4+..+3^{200}\right)-\left(3^1+3^2+3^3+..+3^{199}\right)\)
\(2A=3^{200}-1\)
\(A=\frac{3^{200}-1}{2}\)
Vậy \(3^1+3^2+3^3+..+3^{199}=\frac{3^{200}-1}{2}\)

A = 1
ngu thế