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Những câu hỏi liên quan
VS
4
VD
1
DT
Đỗ Thanh Hải
CTVVIP
13 tháng 8 2021
44 diet
45 medical
46 skillful
47 may
48 much
49 either
50 taking
Ex1
0 Lan is in grade 7
1 She likes learning E
2 She always wants to improve her E
3 Last week, she bought an English-Vietnamese dictionary
4 She often uses it for reading
5 Now she speaks E well
EX2
0 Viet is my friend
1 He likes playing sports very much
2 In his free time, he often plays soccer with his friends
3 He likes watching soccer matches on TV
4 He also likes fishing
5 On the weekends he often goes fishing with his father or brother
VQ
31 tháng 3 2022
( 125 x 0,75 + 125 x 25% ) x ( 9 x 11 - 0,9 x100 - 0,9 x10)
=( 125 x 0,75 + 125 x 25% ) x 0
= 0
MH
4
TT
2
7 tháng 12 2021
a: Để A là số nguyên thì \(2n-3\in\left\{1;-1\right\}\)
hay \(n\in\left\{2;1\right\}\)
7 tháng 12 2021
\(a,A=\dfrac{-3\left(2n-3\right)-8}{2n-3}=-3-\dfrac{8}{2n-3}\in Z\\ \Leftrightarrow2n-3\inƯ\left(8\right)=\left\{-1;1\right\}\left(2n-3\text{ lẻ}\right)\\ \Leftrightarrow n\in\left\{1;2\right\}\)
\(b,\dfrac{ab}{a+2b}=\dfrac{3}{2}\Leftrightarrow\dfrac{a+2b}{ab}=\dfrac{1}{b}+\dfrac{2}{a}=\dfrac{2}{3}\\ \dfrac{bc}{b+2c}=\dfrac{4}{3}\Leftrightarrow\dfrac{b+2c}{bc}=\dfrac{1}{c}+\dfrac{2}{b}=\dfrac{3}{4}\\ \dfrac{ca}{c+2a}=3\Leftrightarrow\dfrac{c+2a}{ca}=\dfrac{1}{a}+\dfrac{2}{c}=\dfrac{1}{3}\)
Cộng vế theo vế \(\Leftrightarrow\dfrac{3}{a}+\dfrac{3}{b}+\dfrac{3}{c}=\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{7}{4}\)
\(\Leftrightarrow3\left(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}\right)=\dfrac{7}{4}\\ \Leftrightarrow\dfrac{ab+bc+ca}{abc}=\dfrac{7}{12}\\ \Leftrightarrow T=\dfrac{abc}{ab+bc+ca}=\dfrac{12}{7}\)
MK
1
YN
20 tháng 6 2022
\(a)\)
\(A=\left(m-1\right)^3-\left(m-2\right)^3\)
\(=\left(m^3-3m^2+3m-1\right)-\left(m^3-6m^2+12m-8\right)\)
\(=m^3-3m^2+3m-1-m^3+6m^2-12m+8\)
\(=3m^2-9m+7\)
\(B=\left(3m-1\right)\left(3m+1\right)\)
\(=9m^2-1\)
\(\dfrac{1}{9}A=B-7\)
\(\Rightarrow\dfrac{1}{9}\left(3m^2-9m+7\right)=9m^2-1-7\)
\(\Rightarrow3m^2-9m+7=81m^2-72\)
\(\Rightarrow78m^2+9m-79=0\)
\(\Rightarrow m=\dfrac{-9\pm\sqrt{24729}}{156}\)
\(b)\)
\(A< B\)
\(\Rightarrow3m^2-9m+7< 9m^2-1\)
\(\Rightarrow6m^2+9m-8>0\)
\(\Rightarrow\left[{}\begin{matrix}m>\dfrac{-9+\sqrt{273}}{12}\\m< \dfrac{-9-\sqrt{273}}{12}\end{matrix}\right.\)
9 tháng 8 2023
uses crt;
var st,k,t:string;
d,dem,i:integer;
begin
clrscr;
readln(st);
d:=length(st);
k='';
dem=1;
for i:=2 to d do
begin
if st[i]=st[i-1] then inc(dem);
if st[i]<>st[i-1] then
btegin
str(dem,t);
if dem>1 then k:=k+t+st[i-1];
else k:=k+st[i-1];
dem=1;
end;
if (i=d) then
begin
str(dem,t);
if dem>1 then k:=k+t+st[i];
else k:=k+st[i];
end;
end;
write(k);
readln;
end.
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