65 nha

\(\frac{-5}{8}+\frac{7}{2}+\frac{-23}{8}< \frac{-1}{3}+1+\frac{7}{3}\)

\(\Rightarrow0< x< \frac{-5}{3}\)

Vì \(x\in N\Rightarrow x=1\)

1/5 MŨ 2 X 1/4 + 1/20

= 1/25 X 1/4 +1/20
= 1/100 +1/20
= 3/50

\(\left(\frac{1}{5}\right)^2\cdot\frac{1}{4}+\frac{1}{20}=\frac{1}{25}\cdot\frac{1}{4}+\frac{1}{20}=\frac{1}{100}+\frac{5}{100}=\frac{6}{100}=\frac{3}{50}\)

\(\frac{57}{89}=\frac{89-32}{89}=1-\frac{32}{89}\)

\(\frac{31}{64}=\frac{64-33}{64}=1-\frac{33}{64}\)

Có \(\frac{32}{89}< \frac{33}{64}\)suy ra \(\frac{57}{89}>\frac{31}{64}\).

Giúp với mn

xin lỗi em mới lớp 2 thôi ạ em thật sự xin lỗi anh ạ

4,6666666666666

\(\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{79.80}\)

\(=\)\(\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+...+\frac{1}{79}-\frac{1}{80}\)

\(=\frac{1}{4}-\frac{1}{80}\)

\(=\frac{20}{80}-\frac{1}{80}\)

\(=\frac{19}{80}\)

\(\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{78.79}+\frac{1}{79.80}\)

\(=\frac{4-3}{3.4}+\frac{5-4}{4.5}+\frac{6-5}{5.6}+...+\frac{79-78}{78.79}+\frac{80-79}{79.80}\)

\(=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{78}-\frac{1}{79}+\frac{1}{79}-\frac{1}{80}\)

\(=\frac{1}{3}-\frac{1}{80}=\frac{77}{240}\)

4 nhé tàn số 4 hoài

TL:

2+2=4

HT

-10122599,52

bằng -10122649,451169147556582277278997 ok nha :)))