\(=1-2\left(\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{8}-\dfrac{1}{9}\right)\)
\(=1-2\cdot\dfrac{7}{18}=\dfrac{18}{18}-\dfrac{14}{18}=\dfrac{4}{18}=\dfrac{2}{9}\)
2/1.2+2/2.3+2/3.4+2/4.5+2/5.6+2/6.7+2/7.8+2/8.9+2/9.10 =?
(1/1.2+1/2.3+1/3.4+.....+1/8.9+1/9.10).100-[5/2:(x+206/100):1/2=89
tìm x
(1/1.2+1/2.3+1/3.4+....+1/8.9+1/9.10).100-[5/2:(x+206/100)]:1/2=89
tìm x hộ mình với
(1/1.2 +1/2.3 1/3.4 + ....+1/8.9) x=23/45
(1/1.2 +1/2.3 1/3.4 + ....+1/8.9) x=23/45
Tính A=1.2+2.3+3.4+4.5+...+8.9+9.10
Tính tổng : a)A=1^2+3^2+5^2+7^2+.....+99^2
b)A=1.2+2.3+3.4+4.5+5.6+6.7+7.8+8.9+9.10
C=A+10.11
Tính giá trị của C
A = 1.2+2.3+3.4+4.5+5.6+6.7+7.8+8.9+7.10
⇒ tự luận
Tính
E= 1.2 + 2.3 + 3.4 +...+ 8.9 + 9.10
