Các câu hỏi tương tự
frac{1}{2^2}+frac{1}{4^2}+frac{1}{6^2}+..+frac{1}{100^2}frac{1}{2^2}left(1+frac{1}{2^2}+frac{1}{3^2}+...+frac{1}{50^2}right)Có frac{1}{2^2} frac{1}{1.2}1-frac{1}{2} frac{1}{3^2} frac{1}{2.3}frac{1}{2}-frac{1}{3}....v........v............ frac{1}{50^2} frac{1}{49.50}frac{1}{49}-frac{1}{50}Cộng lại 1+frac{1}{2^2}+frac{1}{3^2}+...+frac{1}{50^2} 1+1-frac{1}{2}+frac{1}{2}-frac{1}{3}+...+frac{1}{49}-frac{1}{50}2-frac{1}{50}Rightarrow VT frac{1}{2^2}left(2-frac{1}{50}right)frac{1}{2...
Đọc tiếp
\(\frac{1}{2^2}+\frac{1}{4^2}+\frac{1}{6^2}+..+\frac{1}{100^2}=\frac{1}{2^2}\left(1+\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}\right)\)
Có \(\frac{1}{2^2}< \frac{1}{1.2}=1-\frac{1}{2}\) \(\frac{1}{3^2}< \frac{1}{2.3}=\frac{1}{2}-\frac{1}{3}\)....v........v............ \(\frac{1}{50^2}< \frac{1}{49.50}=\frac{1}{49}-\frac{1}{50}\)
Cộng lại \(1+\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}< 1+1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{49}-\frac{1}{50}=2-\frac{1}{50}\)
\(\Rightarrow VT< \frac{1}{2^2}\left(2-\frac{1}{50}\right)=\frac{1}{2}-\frac{1}{2^2.50}< \frac{1}{2}\left(Đpcm\right)\)
chứng tỏ :
1/1*2 + 1/3*4+.......+1/49*50 = 1/26 +1/27 +.......+1/50
1+10-2+84-2+100+84+60-50+1+63-4
tính nhanh phân số:
\(\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+......=\frac{1}{1+2+3+.....+50}\)
18 tháng 9 2018 lúc 17:52
tính nhanh:
1+2+3+4+...+50
1+2+3+4+5+6...+50=?
1+2+3+4...+100=?
ai ib vs mk ko ??
Tổng: 1+2+3+4+5+6+7+8+9.............+50=
Tổng: 1+2+3+4+5+6+7+8+9.............+50=
Tính nhẩm:
24 + 1 …
64 – 4 …
80 + 6 …
73 + 2 …
36 – 5 …
86 – 6 …
50 + 8 …
47 – 1 …
86 – 80 …
Đọc tiếp
Tính nhẩm:
| 24 + 1 = … | 64 – 4 = … | 80 + 6 = … |
| 73 + 2 = … | 36 – 5 = … | 86 – 6 = … |
| 50 + 8 = … | 47 – 1 = … | 86 – 80 = … |