1 . tính nhanh
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+...+\frac{1}{36x37x38}+\frac{1}{37x38x39}\)
giúp nha
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4x}+\frac{1}{3x4x5}+...+\frac{1}{36x37x38}+\frac{1}{37x38x39}\)
giúp nha
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+...\frac{1}{36x37x38}+\frac{1}{37x38x39}=?\)
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+...+\frac{1}{48x49x50}\)
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+...\frac{1}{36x37x38}+\frac{1}{37x38x39}\)chú ý đây là tính nhanh
Chứng minh:
\(\frac{1}{1x2x3}+\frac{1}{2x3x4}+\frac{1}{3x4x5}+....+\frac{1}{98x98x100}\)<1
Ai làm nhanh và đúng mình tick cho!!:)
TÍNH NHANH:
a]S=3+1/3x6+1/6x9+1/9x12+...+1/96x99
b]S=1/1x2x3+1/2x3x4+1/3x4x5+...+1/37x38x39
\(\frac{2}{1x2x3}+\frac{2}{2x3x4}+\frac{2}{3x4x5}+...+\frac{2}{48x49x50}\)
\(A=\frac{1}{1x2x3}+\frac{1}{2x3x4}+...+\frac{1}{2018x2019x2020}+\frac{1}{2x2019x2020}\)
A=?
