1+1+2+4
(1+1 1/4+1 1/2+1 3/4+2+2 1/4+2 1/2+2 3/4+...+4 3/4):23
Chứng tỏ
A=1/2^2+1/3^2+1/4^2+...+1/2014^2<3/4
B=1/2.3+1/3.4+...+1/6.7<1/2
C=4/1.5+4/5.9+4/9.13+4/13.17+4/17.21<1
D=1/2^2+1/3^3+1/4^2+...+1/10^2<1
1+1+1+1+1+1+2+2+2+2+2+2+3+3+3+4+4+4+4+4+4+4+4+1234567890 có chia hết cho 3 không?
Tính:
4 - 1 = 4 - 2 = 3 + 1 = 1 + 2 =
3 - 1 = 3 - 2 = 4 - 3 = 3 - 1 =
2 - 1 = 4 - 3 = 4 - 1 = 3 - 2 =
Thực hiện phép trừ rồi điền kết quả vào chỗ trống.
4 - 1 = 3 4 - 2 = 2 3 + 1 = 4 1 + 2 = 3
3 - 1 = 2 3 - 2 = 1 4 - 3 = 1 3 - 1 = 2
2 - 1 = 1 4 - 3 = 1 4 - 1 = 3 3 - 2 = 1
1. (1+1/2).(1+1/2^2).(1+1/2^3)....(1+1/2^100) < 3
2. 1/(5+1)+2/(5^2+1)+4/(5^4+1)+...+ 1024/(5^1024+1) <1/4
3. 3/(1!+2!+3!)+4/(2!+3!+4!)+...+100/(98!+99!+100!) <1/2
??????????????????????????????????????????????
Lần đầu post, mình quên mất chưa nêu câu hỏi. Nhờ các bạn chứng minh dùm 3 câu trên với, cám ơn nhiều ah!
1.\(\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)+...+\left(1+\frac{1}{2^{100}}\right)\)
Đặt \(A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\)
\(\Rightarrow2A=1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}\)
\(\Rightarrow2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\right)\)
\(\Rightarrow A=1-\frac{1}{2^{100}}\)
Thấy:\(\frac{1}{2^{100}}>0\Rightarrow1-\frac{1}{2^{100}}< 1\)
\(\Rightarrow A< 1\)
Ta có:\(\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)...\left(1+\frac{1}{2^{100}}\right)=A+100< 1+100=101\)
\(101>\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)...\left(1+\frac{1}{2^{100}}\right)\ge100\)
\(\Rightarrow\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)...\left(\frac{1}{2^{100}}\right)>\left(\frac{101}{100}\right)^{100}>3\)
*Cách khác:
\(\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)+...+\left(1+\frac{1}{2^{100}}\right)\)
\(=\frac{2+1}{2}.\frac{2^2+1}{2^2}....\frac{2^{100}+1}{2^{100}}\)
Ta thấy:
\(\frac{2+1}{2}>\frac{2^2+1}{2^2}>....>\frac{2^{100}+1}{2^{100}}\)
\(\Rightarrow\frac{2+1}{2}>\frac{2+1}{2}.\frac{2^2+1}{2^2}....\frac{2^{100}+1}{2^{100}}\)
Mà \(\frac{2+1}{2}< 3\)
\(\Rightarrow\frac{2+1}{2}.\frac{2^2+1}{2^2}....\frac{2^{100}+1}{2^{100}}< 3\)
\(\Rightarrow\left(1+\frac{1}{2}\right)\left(1+\frac{1}{2^2}\right)\left(1+\frac{1}{2^3}\right)+...+\left(1+\frac{1}{2^{100}}\right)< 3\)
>, <, =?
2 … 4 – 1 | 3 – 2 … 3 – 1 |
3 … 4 – 1 | 4 – 1 …4 – 2 |
4 … 4 – 1 | 4 – 1 … 3 + 0 |
Lời giải chi tiết:
2 < 4 – 1 | 3 – 2 < 3 – 1 |
3 = 4 – 1 | 4 – 1 > 4 – 2 |
4 > 4 – 1 | 4 – 1 = 3 + 0 |
< <
= >
câu trả lời đây
(1+1 và 1/4+1 và 1/2+1 và 3/4+2+2 và 1/4+2 và 1/2+2 và 3/4+...+4 và 3/4):23
>, <, = ?
4 – 1 … 2 | 4 – 3 … 4 – 2 |
4 – 2 … 2 | 4 – 1 … 3 + 1 |
3 – 1 … 2 | 3 – 1 … 3 – 2 |
Lời giải chi tiết:
4 – 1 > 2 | 4 – 3 < 4 – 2 |
4 – 2 = 2 | 4 – 1 < 3 + 1 |
3 – 1 = 2 | 3 – 1 > 3 – 2 |
4-1 > 2
4-2 = 2
4-3 < 4-2
4-1 < 3+1
4 – 1 > 2 | 4 – 3 < 4 – 2 |
4 – 2 = 2 | 4 – 1 < 3 + 1 |
3 – 1 = 2 | 3 – 1 > 3 – 2 |
>, <, = ?
4 – 1 … 2 | 4 – 3 … 4 – 2 |
4 – 2 … 2 | 4 – 1 … 3 + 1 |
3 – 1 … 2 | 3 – 1 … 3 – 2 |
Lời giải chi tiết:
4 – 1 > 2 | 4 – 3 < 4 – 2 |
4 – 2 = 2 | 4 – 1 < 3 + 1 |
3 – 1 = 2 | 3 – 1 > 3 – 2 |