6A=6.(1/1.7 + 1/7.13 + 1/13.19 + 1/19.25 + 1/25.31 + 1/31.37)
6A=6/1.7 + 6/7.13 + 6/13.19 + 6/19.25 + 6/25.31 + 6/31.37
6A=(1/1 - 1/7) + (1/7 - 1/13) + (1/13 - 1/19) + (1/19 - 1/25) + (1/25 - 1/31) + (1/31 - 1/37)
6A=1/1 - 1/37 = 36/37
A=36/37 : 6 = 6/37
Bài 1 : TÍnh Tổng
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{775}+\frac{1}{1147}\)
\(A=\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{775}+\frac{1}{1147}\) = ?
Tính:
C=\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{775}+\frac{1}{1147}\)
D=\(\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{5.7}+.......+\frac{3}{49.51}\)
tính tổng \(\frac{1}{7}\)+ \(\frac{1}{91}\) + \(\frac{1}{247}\) + \(\frac{1}{475}\)+ \(\frac{1}{775}\)+ \(\frac{1}{1147}\)
Tính tổng :
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
P/S :cơ hội kiếm điểm nè
Tính :
\(\frac{1}{7}\)+\(\frac{1}{91}\)+\(\frac{1}{247}\)+\(\frac{1}{475}\)+ \(\frac{1}{775}\)+\(\frac{1}{1147}\)
tính tổng các phân số theo cách nhanh nhất
a) \(\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{5.7}+...+\frac{3}{49.51}\)
b) \(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{775}+\frac{1}{1147}\)
ghi rỏ cách làm nha mình tick cho nah
Cho\(S=\frac{5^2}{1.6}+\frac{5^2}{6.11}+...+\frac{5^2}{26.31}\)
Cho \(L=\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{775}+\frac{1}{1147}\)
giúp mình nè : tính nhanh\(a,\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{775}+\frac{1}{1147}\)
\(b,74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}.\frac{7}{90}\)
CẢM ƠN CÁC BẠN!!!
