\(\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}\)
= \(\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{1}{4}+\dfrac{1}{5}-\dfrac{1}{5}+\dfrac{1}{6}-\dfrac{1}{6}+\dfrac{1}{7}-\dfrac{1}{7}+\dfrac{1}{8}\)
= \(\dfrac{1}{2} +\dfrac{1}{8}\)
\(= \dfrac{5}{8}\)
Tính :
Làm hộ với lưu ý giiar chi tiết hộ mình
#kí
G=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+....+\frac{1}{99.100}\)
E=\(\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+....+\frac{20}{53.55}\)
D=\(\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
Bài 1: Tìm x biết: \(\left(-2\right)\cdot\left(x+1\right)-3\cdot\left(1-x\right)=4\)
Bài 2: Chứng minh rằng: \(\frac{3}{5}< \frac{1}{31}+\frac{1}{32}+\frac{1}{33}+...+\frac{1}{60}< \frac{4}{5}\)
điền số thích hợp vào ô vuông:
a)\(\frac{1}{3}=\frac{?}{?}\)
b)\(\frac{-1}{4}\)\(\frac{?}{?}\)
c)\(1=\frac{ }{3}=\frac{ }{-4}=\frac{ }{6}=\frac{-9}{ }\)
d)-2=\(\frac{ }{2}=\frac{ }{-3}=\frac{ }{5}=\frac{-5}{ }=\frac{7}{ }\)
Chứng minh rằng \(\frac{1}{3}-\frac{2}{3^2}+\frac{3}{3^3}-\frac{4}{3^4}+\frac{5}{3^5}-.........+\frac{99}{3^{99}}-\frac{100}{3^{100}}< \frac{3}{16}\)
=5−4?
a.\frac{1}{2} + a.\frac{1}{3} - a.\frac{1}{4}a.21+a.31−a.41
Phân số xen giữa \(\frac{1}{10}\) và \(\frac{-1}{10}\)
tính
a)1/2.3+1/3.4+1/4.5+....+1/99.100
b) cho M=1/101+1/102+1/103+...+1/200.Chứng minh:M>7/12
Tính tổng:
a)\(\dfrac{1}{5.6}\)+\(\dfrac{1}{6.7}\)+\(\dfrac{1}{7.8}\)+...+\(\dfrac{1}{24.25}\)
b)\(\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+...+\dfrac{2}{99.101}\)
tính tổng
A = \(\frac{6}{5.8}+\frac{22}{8.19}+\frac{24}{19.31}+\frac{140}{31.101}+\frac{198}{101.200}\)
ai nhanh dc tick nhé
nhanh dc 5 tick
