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Bài 1
a) S = 1 + 2 + 2² + 2³ + ... + 2²⁰²³
2S = 2 + 2² + 2³ + 2⁴ + ... + 2²⁰²⁴
S = 2S - S = (2 + 2² + 2³ + ... + 2²⁰²⁴) - (1 + 2 + 2² + 2³)
= 2²⁰²⁴ - 1
b) B = 2²⁰²⁴
B - 1 = 2²⁰²⁴ - 1 = S
B = S + 1
Vậy B > S
a,
\(S=1+2+2^2+...+2^{2023}\)
\(2S=2+2^2+2^3+...+2^{2024}\)
\(\Rightarrow S=2^{2024}-1\)
b.
Do \(2^{2024}-1< 2^{2024}\)
\(\Rightarrow S< B\)
2.
\(H=3+3^2+...+3^{2022}\)
\(\Rightarrow3H=3^2+3^3+...+3^{2023}\)
\(\Rightarrow3H-H=3^{2023}-3\)
\(\Rightarrow2H=3^{2023}-3\)
\(\Rightarrow H=\dfrac{3^{2023}-3}{2}\)
1−2−3+4+5−6−7+8+...+21−22−23+24+25
= (1 - 2 - 3 + 4) + (5 - 6 - 7 + 8) + ... + (21 - 22 - 23 + 24) + 25=(1−2−3+4)+(5−6−7+8)+...+(21−22−23+24)+25
= 0 + 0 + ... + 0 + 25=0+0+...+0+25
= 25
a) \(A=2\left(1+2+2^2+...+2^{2022}+2^{2023}\right)⋮2\left(đpcm\right)\)
b) \(A=2\left(1+2\right)+2^3\left(1+2\right)+...+2^{2023}\left(1+2\right)\)
\(=2.3+2^3.3+...+2^{2023}.3\)
\(=3\left(2+2^3+...+2^{2023}\right)⋮3\left(đpcm\right)\)
A) A=2+22+23+...+22023+22024
A=2(1+2+22+...+22022+22023)⋮2
B) A=2+22+23+...+22023+22024
A=(2+22)+...+(22023+22024)
A=2(1+2)+...+22023(1+2)
A=2.3+...+22023.3
A=3(2+...+22023)⋮3
Ta có: \(\frac{12}{13}=1-\frac{1}{13}\) ; \(\frac{22}{23}=1-\frac{1}{23}\)
Do \(\frac{1}{13}>\frac{1}{23}\)nên \(1-\frac{1}{13}< 1-\frac{1}{23}\)
Vậy \(\frac{12}{13}< \frac{22}{23}\)
\(\frac{12}{13}=1-\frac{1}{13};\frac{22}{23}=1-\frac{1}{23}\)
Có \(1-\frac{1}{13}< 1-\frac{1}{23}\Rightarrow\frac{12}{13}< \frac{22}{23}\)
a: \(A=1+2+2^2+...+2^{2023}\)
=>\(2A=2+2^2+2^3+...+2^{2024}\)
=>\(2A-A=2^{2024}+2^{2023}+...+2^2+2-2^{2023}-2^{2022}-...-2^2-2-1\)
=>\(A=2^{2024}-1\)
b: \(A=\left(1+2\right)+2^2+2^3+...+2^{2023}\)
\(=3+2^2\left(1+2\right)+...+2^{2022}\left(1+2\right)\)
\(=3\left(1+2^2+...+2^{2022}\right)⋮3\)
10x+23 chia het cho 2x+1
=>5(2x+1)+18 chia het cho 2x+1
5(2x+1) chia het cho 2x+1
=>18 chia het cho 2x+1
=>2x+1 thuoc Ư(18)={1;2;3;6;9;18}
voi 2x+1=1=>x=0
voi 2x+1=2=>(loai)
voi 2x+1=3=>x=1
voi 2x+1=6=>(loai)
voi 2x+1=9=>x=4
voi 2x+1=18=>(loai)
vay x={0;1;4}
1 - 2 - 3 + 4 + 5 - 6 - 7 + 8 + ... + 21 - 22 - 23 + 24 + 25.
=(1 - 2 - 3 + 4) + (5 - 6 - 7 + 8) + ......+ ( 21 - 22 - 23 + 24)+25
= 0+0+0+......+0+25
=0+25
=25
~HT~
@Jennie
mk nghĩ ko cần giải thik đâu
vì mk ghép các cặp lại để ra kq bằng 0
sau đó cộng thêm 25
là ra kq 25
~HT
#Jennie
Coi A=1+2+22+...+22024
B=5.22023
�=1+2+22+...+22022
A=1+2+22+...+22024�=1+2+22+...+22022
⇒2A=2+22+...+22024⇒2�=2+22+...+22023
⇒2A−A=22024−1⇒2�−�=22023−1
⇒A=22024−1⇒�=22023−1
⇒A<22024=2
.22023=2.22023<5.22023⇒�<22023=22.22021=4.22021<52021
⇒A<B