\(A=\frac{2}{5\cdot9}+\frac{2}{9\cdot13}+...+\frac{2}{55\cdot59}\)
\(A=2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{55}-\frac{1}{59}\right)\)
\(A=2\left(\frac{1}{5}-\frac{1}{59}\right)\)
\(A=2\left(\frac{59}{295}-\frac{5}{295}\right)\)
\(A=2\cdot\frac{54}{295}\)
\(A=\frac{536}{295}\)
Tính tổng sau : S = 2/5.9 +2/9.13 + 2/13.17 +.....+ 2/97.101
Giúp mình nha mình cầm gấp
Tính:
1.5 + 5.9 + 9.13 + 13.17 + ................ + 97.101
Tính:
1.5 + 5.9 + 9.13 + 13.17 + ................ + 97.101
Tính tổng S= 1/5.9+1/9.13+1/13.17+1/17.21+1/21.25
tìm x biết:
a) 7/x + 4/5.9+4/9.13+4/13.17+...+4/41.45=29/45
b) x/2008 - (2/20+2/30+2/42+...+2/240)=5/8
\(\dfrac{1}{5.9}+\dfrac{1}{9.13}+\dfrac{1}{13.17}+\dfrac{1}{17.21}+\dfrac{1}{21.25}\) (Tính tổng)
Tìm x biết:
(x-1)2+\(\dfrac{1}{5.9}+\dfrac{1}{9.13}+\dfrac{1}{13.17}+...+\dfrac{1}{41.45}=\dfrac{49}{900}\)
Giúp mk với chiều mai mk thi rùi =((
X+8/5.9+8/9.13+8/13.17+....+8/41.45= -74/45
x + 4/5.9 + 4/9.13 + 4/13.17 + ... + 4/41.45 = -37/45
