Trả lời:
\(A=\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{2018.2019.2020}+\frac{1}{2.2019.2020}\)
\(A=\frac{1}{2}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+...+\frac{2}{2018.2019.2020}+\frac{2}{2.2019.2020}\right)\)
\(A=\frac{1}{2}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+...+\frac{1}{2018.2019}-\frac{1}{2019.2020}+\frac{1}{2019.2020}\right)\)
\(A=\frac{1}{2}.\frac{1}{1.2}\)
\(A=\frac{1}{4}\)
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+...\frac{1}{36x37x38}+\frac{1}{37x38x39}=?\)
1 . tính nhanh
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+...+\frac{1}{36x37x38}+\frac{1}{37x38x39}\)
giúp nha
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+...\frac{1}{36x37x38}+\frac{1}{37x38x39}\)chú ý đây là tính nhanh
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+...+\frac{1}{48x49x50}\)
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+....+\frac{1}{37x38x39}\)
Chứng minh:
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+....+\frac{1}{98x98x100}\)<1
Ai làm nhanh và đúng mình tick cho!!:)
\(\frac{2}{1x2x3}+\frac{2}{2x3x4}+\frac{2}{3x4x5}+...+\frac{2}{48x49x50}\)
1. Tính tổng
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+.....+\frac{1}{18x19x20}\)
2. Tính nhanh
B = 1 x 1 + 2 x 2 + 3 x 3 + ......+ 100 x 100
3. Tính tổng
A = 4 + 16 + 36 + 64 +.....+ 10000
4. Tính tổng:
M = 1 + 9 + 25 + 49 + 9801
5. Tính nhanh:
\(\left(\frac{1}{51}+\frac{1}{52}+\frac{1}{53}+....+\frac{1}{100}\right):\left(\frac{1}{1x2}+\frac{1}{3x4}+\frac{1}{99x100}\right)\)
Nhớ cho mình cách giải nha. Ai làm nhanh, làm đúng sẽ được 10 tick
Tính A\(\frac{1x2x3+2x4x6+4x8x12+8x16x24}{2x3x4+4x6x8+8x12x16+8x24x32}\)
