\(\dfrac{1}{4}+\left(\dfrac{-1}{2}+\dfrac{2}{3}\right)\\ =\dfrac{1}{4}+\left(\dfrac{-3}{6}+\dfrac{4}{6}\right)\\ =\dfrac{1}{4}+\dfrac{1}{6}\\ =\dfrac{3}{12}+\dfrac{2}{12}\\ =\dfrac{5}{12}\)
cho M=1/2^2+1/3^2+1/4^2+....+1/50^2
CMR:M<3/4
Bài 1:
a) Chứng tỏ rằng : 200 - (3+2/3+2/4+....+2/100)
--------------------------------------- = 2
1/2+2/3+3/4+....+9/100
b) Cho B =5/2.1 + 4/1.11 + 3/11.2 + 1/2.15 + 15/4.43 + 13/43
Chứng tỏ rằng B > 3
2/5 < 1/2^2 +1/3^2 +1/4^2 +...+ 1/9^2 <8/9
Cho A=3/1*2*3+3/2*3*4+3/3*4*5+.........+3/2015*2016*2017.
So sánh A với 1.
-2/5 + (4/6 - 1/15) - -1/10
1/2 - (-7/3 + 2/5) + 1/8
CHỨNG TỎ:
\(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{10^2}< 1\)
Tính tổng: 1 + 1/2 + 1/3 + 1/4 +...+ 1/63.
Cho A = 1/99 + 2/98 + 3/97 + ... + 99/1 / 1/2 + 1/3 + 1/4 + ... + 1/100
B = 94 - 1/7 - 2/8 - 3/9 - ... - 94/100 / 1/35 + 1/40 + 1/45 + ... + 1/500
Tính:A - 2.F
tính tổng:
a,1/2 x 3+1/2 x 4+1/2 x 5+...+1/9 x 10
b,3/2 x 5+3/6 8+...+3/23 x 28
giải nhanh hộ mik nha
