so sánh S=1+1/2+1/3+1/4+…+1/64 với 4
so sánh S=1+1/2+1/3+...+1/63+1/64 với 4
Cho S = 4^0 + 4^1 + 4^2 + 4^3 +...+ 4^35Hãy so sánh 3S với 64^12
\(4^0+4^1+4^2+4^3+...+4^{35}\\ 4S=4^1+4^2+4^3+4^4+...+4^{36}\\ 4S-S=\left(4^1+4^2+4^3+4^4+...+4^{36}\right)-\left(4^0+4^1+4^2+4^3+...+4^{35}\right)\\ 3S=4^{36}-1=64^{12}-1\\ Vì64^{12}-1< 64^{12}\\ \Rightarrow3S< 64^{12}\)
Ta có: \(64^{12}=\left(4^3\right)^{12}=4^{36}\)
\(S=4^0+4^1+...+4^{34}+4^{35}\)
\(\Rightarrow4S=4^1+4^2+...+4^{35}+4^{36}\)
\(\Rightarrow4S-S=4^{36}-4^0\)
\(\Rightarrow3S=4^{36}-1< 4^{36}\)
Vậy \(3S< 64^{12}\)
giải giúp mình bài toán sau đc ko:
So sánh S=1+1/2+1/3+...+1/63+1/64 với 4
cho S=4^0+4^1+4^2+...+4^35
so sánh 3S với 64^12
Ta co:S=4^0+4^1+4^2+...+4^35
=>4S=4^1+4^2+...+4^36
=>4S-S=(4^1+4^2+...+4^36)-(4^0+4^1+...+4^35)
hay 3S=4^36-1
3S=64^12-1<64^12
Vay 3S<64^12
co gi hoi mik de mik lam tiep nhe
bye...
Cho S = 4^0+4^1+4^2+4^3+4^4+....+4^35
Hãy so sánh 3S với 64^12
*Chú thích: 4^1= bốn mũ một(tại điện thoại ko có dấu mũ )
\(S=4^0+4^1+4^2+4^3+...+4^{35}\)
\(4S=4^1+4^2+4^3+...+4^{36}\)
\(4S-S=(4^1+4^2+4^3+...+4^{36})-(4^0+4^1+4^2+4^3+...+4^{35})\)
\(3S=4^{36}-4^0\)
\(S=4^{36}-1\)
\(\text{Ta thấy :}64^{12}=(4^3)^{12}=4^{36}\)
\(\text{Mà }4^{36}-1>4^{36}\text{ nên }3S>A\)
Bài 1 : So Sánh
A = 4 * (3 ^ 2 +1) * (3 ^ 4 + 1 ) * (3 ^ 8 + 1) * . .. * (3 ^ 64 + 1 )
cho D=1/7^2-2/7^3+3/7^4-4/7^5+.....+201/7^202-202/7^203. Hãy so sánh D với 1/64.
em nên gõ công thức trực quan để được hỗ trợ tốt nhất nhé
D = \(\dfrac{1}{7^2}\) - \(\dfrac{2}{7^3}\) + \(\dfrac{3}{7^4}\) - \(\dfrac{4}{7^5}\) +........+ \(\dfrac{201}{7^{202}}\) - \(\dfrac{202}{7^{203}}\)
7 \(\times\) D = \(\dfrac{1}{7}\) - \(\dfrac{2}{7^2}\) + \(\dfrac{3}{7^3}\) - \(\dfrac{4}{7^4}\) + \(\dfrac{5}{7^5}\) -.......- \(\dfrac{202}{7^{202}}\)
7D +D = \(\dfrac{1}{7}\) - \(\dfrac{1}{7^2}\) + \(\dfrac{1}{7^3}\) - \(\dfrac{1}{7^4}\) + \(\dfrac{1}{7^5}\) -.........-\(\dfrac{1}{7^{202}}\) - \(\dfrac{202}{7^{203}}\)
D = ( \(\dfrac{1}{7}\) - \(\dfrac{1}{7^2}\) + \(\dfrac{1}{7^3}\) - \(\dfrac{1}{7^4}\) + \(\dfrac{1}{7^5}\) -.........-\(\dfrac{1}{7^{202}}\) - \(\dfrac{202}{7^{203}}\)) : 8
Đặt B = \(\dfrac{1}{7}\) - \(\dfrac{1}{7^2}\) + \(\dfrac{1}{7^3}\) - \(\dfrac{1}{7^4}\) + \(\dfrac{1}{7^5}\) -........+\(\dfrac{1}{7^{201}}\).-\(\dfrac{1}{7^{202}}\)
7 \(\times\) B = 1 - \(\dfrac{1}{7}\)+\(\dfrac{1}{7^2}\) - \(\dfrac{1}{7^3}\) + \(\dfrac{1}{7^4}\) - \(\dfrac{1}{7^5}\) +.........- \(\dfrac{1}{7^{201}}\)
7B + B = 1 - \(\dfrac{1}{7^{202}}\)
B = ( 1 - \(\dfrac{1}{7^{202}}\)) : 8
D = [ ( 1 - \(\dfrac{1}{7^{202}}\)): 8 - \(\dfrac{202}{7^{203}}\)] : 8
D = \(\dfrac{1}{64}\) - \(\dfrac{1}{64.7^{202}}\) - \(\dfrac{202}{7^{203}.8}\) < \(\dfrac{1}{64}\)
Cho S= 40+41+4243+...+435
Hãy so sánh 3S với 6412
4S=4.(40+41+43+...+435)
4S=41+42+...+436
4S-S=(41-41)+(42-42)+...+(335-335)+336-30
3S=0+0+...+0+336-1
6412=(34)12=336
vỉ 336-1<336 nên 3S<6412
So sánh
A= 4(32+1)(34+1)(38+1).....(364+1) và B=3126-1
p/s: Mìh cần gấp lắm nha^^bạn nào bk giúp mìh
A=4(3^2+1)(3^4+1)(3^8+1)...(3^64+1)
2A=8(3^2+1)(3^4+1)(3^8+1)...(3^64+1)
2A=(3^2-1)(3^2+1)(3^4+1)(3^8+1)...(3^64+1)
2A=(3^4-1)(3^4+1)(3^8+1)...(3^64+1)
2A=(3^8-1)(3^8+1)....(3^64+1)
2A=(3^16-1)...(3^64+1)
......
2A=(3^64-1)(3^64+1)
2A=3^128-1
A=(3^128-1)/2
=> A>B
\(A=4\left(3^2+1\right)\left(3^4+1\right)...\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^2-1\right)\left(3^2+1\right)...\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^4-1\right)\left(3^4+1\right)...\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^8-1\right)\left(3^8+1\right)...\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^{16}-1\right)\left(3^{16}+1\right)...\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^{32}-1\right)\left(3^{32}+1\right)\left(3^{64}+1\right)\)
\(\Leftrightarrow4A=\left(3^{64}-1\right)\left(3^{64}+1\right)\Leftrightarrow4A=3^{128}-1\Leftrightarrow A=\frac{3^{128}-1}{4}\)
Ta có \(\frac{3^{128}-1}{4}< 3^{128}-1\Rightarrow A< B\)
Lâm Huyền:Bạn sai đề rồi B phải là 3128-1 chứ !
Sorry,mình tính sai.Bạn thay 4A thành 2A va các số 4 thành số 2 nhé