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Ta có : \(\frac{1}{4}+\frac{1}{3}:\frac{1}{x}=\frac{11}{12}\)
\(\Rightarrow\frac{1}{3}:\frac{1}{x}=\frac{11}{12}-\frac{1}{4}\)
\(\frac{1}{3}:\frac{1}{x}=\frac{2}{3}\)
\(\frac{1}{x}=\frac{1}{3}:\frac{2}{3}\)
\(\frac{1}{x}=\frac{1}{3}\times\frac{3}{2}\)
\(\frac{1}{x}=\frac{1}{2}\)
=> x = 2
a) \(\frac{x\div3-16}{2}+21=38\)
\(\frac{x\div3-16}{2}=38+21\)
\(\frac{x\div3-16}{2}=59\)
\(x\div3-16=59.2\)
\(x\div3-16=118\)
\(x\div3=118+16\)
\(x\div3=134\)
\(x=134.3\)
\(x=402\)
b) \(\frac{1}{4}+\frac{1}{3}\div\frac{1}{x}=\frac{11}{12}\)
\(\frac{1}{3}\div\frac{1}{x}=\frac{11}{12}-\frac{1}{4}\)
\(\frac{1}{3}\div\frac{1}{x}=\frac{2}{3}\)
\(\frac{1}{x}=\frac{1}{3}\div\frac{2}{3}\)
\(\frac{1}{x}=\frac{1}{2}\)
Vậy x = ....
a,
x.2/7.3/4=5/21
x.3/14=5/21
x=5/21:3/14
x=10/9
b,
x.1/2=1/3
x=1/3:1/2
x=2/3
c,
x:4/5=25/8:5/4
x:4/5=5/2
x=5/2.4/5=2
A, x= 5/25 : 3/4 : 2/7 = 14/15
B, x=1/3 : 1/2 = 2/3
C, x=(25/8 : 5/4)x4/5 = 5/2 x 4/5 = 2
Câu b:
\(\frac{21}{8}:\frac{5}{6}+\frac{1}{2}:\frac{5}{6}\)
= \(\frac{63}{20}+\frac{3}{5}\)
= \(\frac{15}{4}\)
\(\left(\frac{21}{8}+\frac{1}{2}\right):\frac{5}{6}\)
\(\frac{25}{8}:\frac{5}{6}\)
\(\frac{25}{8}.\frac{6}{5}\)
\(\frac{30}{8}\)
Câu 2.
=>x +4<11
=>x=0;1;2;3;4;5;6
=>x +4>9
=>x=6;7;8;9;...
=> x=6
a) X = 15
b) X = 4
c ) X= 23
d) X= 11
( Chỉ là ý kiến riêng thôi nhé, nhận gạch đá )
a) \(\frac{6+x}{33}=\frac{7}{11}\)
=> (6 + x). 11 = 33.7
=> 66 + 11x = 231
=> 11x = 231 - 66
=> 11x = 165
=> x = 165 : 11
=> x = 15
b) 15/26 + x/13 = 46/52
=> x/13 = 23/26 - 15/26
=> x/13 = 4/13
=> x = 4
c) 121/27 x 54/11 < x < 100/21 : 25/126
=> 22 < x < 24
=> x = 23 (vì x là số tự nhiên)
d) 1 < 11/x < 12
=> 11/x \(\in\){2; 3; 4 ; ...; 11}
=> x \(\in\) {11/2; 11/3; ...; 1}
Vì x là số tự nhiên => x = 1
Dấu "." là dấu nhân nhé
\(\frac{1}{2.4}+\frac{1}{4.6}+\frac{1}{6.8}+...+\frac{1}{2016.2018}\)
\(=\frac{1}{2}.\left(\frac{2}{2.4}+\frac{2}{4.6}+...+\frac{2}{2016.2018}\right)\)
\(=\frac{1}{2}.\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{2016}-\frac{1}{2018}\right)\)
\(=\frac{1}{2}.\left(1-\frac{1}{2018}\right)\)
\(=\frac{1}{2}.\frac{2017}{2018}\)
\(=\frac{2017}{4036}\)
\(x.\frac{2}{7}.\frac{3}{4}=\frac{5}{21}\)
\(\frac{3}{14}x=\frac{5}{21}\)
\(x=\frac{5}{21}:\frac{3}{14}\)
\(x=\frac{5}{21}.\frac{14}{3}\)
\(x=\frac{10}{9}\)
Vậy \(x=\frac{10}{9}\)
những câu bài 2 này là tìm x bình thường
(x - 21 x 13) : 11 = 30
=> x - 273 = 330
=> x = 603
vậy_
(627 - 138) : (x : 2) = 163
=> 489 : (x : 2) = 163
=> x : 2 = 3
=> x = 6
vậy_
\(\left(x-21.13\right):11=30\)
\(\left(x-273\right):11=30\)
\(\left(x-273\right)=30.11=330\)
\(x=330+273\)
\(x=603\)
không nói linh tinh nha thánh troll trả lời thì trả lời đi bị trừ điểm đó
\(\frac{5}{9}\) . \(\frac{a}{b}\) - \(\frac{11}{21}\) = \(\frac{4}{21}\)
\(\frac{5}{9}\) . \(\frac{a}{b}\) = \(\frac{4}{21}\) + \(\frac{11}{21}\)
\(\frac{5}{9}\) . \(\frac{a}{b}\) = \(\frac{5}{7}\)
\(\frac{a}{b}\) = \(\frac{5}{7}\) : \(\frac{5}{9}\)
\(\frac{a}{b}\) = \(\frac{9}{7}\)
Vậy \(\frac{a}{b}\) = \(\frac{9}{7}\)
5/9 x a/b-11/21=4/21
<=> 5/9 x a/b=4/21+11/21
<=> 5/9 x a/b = 21/21=1
<=> a/b = 1 : 5/9
<=> a/b=9/5
Vậy a/b=9/5