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a) Ta có : \(\frac{35}{91}\)= \(\frac{5}{13}=\frac{x}{13}\Rightarrow x=5\)
b, ta có
<=>6 (9+x)=5 (13-x)
<=>54+6x=65-5x
<=>6x+5x=65-54
<=>11x=11
<=>x=1
\(\left(a\right)\frac{34-x}{30}=\frac{5}{6}\)
\(\frac{34-x}{30}=\frac{25}{30}\)
34 - x = 25
x = 34 - 25 = 9
\(\left(b\right)\frac{x+13}{34}=\frac{12}{17}\)
\(\frac{x+13}{34}=\frac{24}{34}\)
x + 13 = 24
x = 24 - 13 = 11
\(\left(c\right)\left(x+\frac{1}{3}\right)+\left(x+\frac{1}{9}\right)+\left(x+\frac{1}{27}\right)+\left(x+\frac{1}{81}\right)=\frac{56}{81}\)
\(4x+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}=\frac{56}{81}\)
Đặt \(A=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}\)
Ta có : \(3A=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}\)
\(3A-A=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}-\frac{1}{3}-\frac{1}{9}-\frac{1}{27}-\frac{1}{81}\)
\(2A=1-\frac{1}{81}=\frac{80}{81}\)
\(A=\frac{80}{81}\div2=\frac{40}{81}\)
\(\Rightarrow4x+\frac{40}{81}=\frac{56}{81}\)
\(4x=\frac{56}{81}-\frac{40}{81}\)
\(4x=\frac{16}{81}\)
\(x=\frac{16}{81}\div4=\frac{4}{81}\)
a) x + 5,84 = 9,16
=> x = 9,16 - 5,84
x = 3,32
b) \(x=\frac{1}{5}-\frac{3}{7}\)
=> x = \(\frac{-8}{35}\)
c) \(\frac{x}{5}=\frac{5}{6}-\frac{13}{30}\)
=> \(\frac{x}{5}=\frac{2}{5}\)
=> \(x=5\)
d) \(x+\frac{3}{4}=\frac{4}{5}\)
=> x = \(\frac{4}{5}-\frac{3}{4}\)
x = \(\frac{1}{20}\)
e) \(\frac{x}{7}=\frac{7}{8}-\frac{25}{56}\)
=> \(\frac{x}{7}=\frac{3}{7}\)
=> x = 3
t i c k nhé!! 426356457467568768467356457568578769578956
Câu a,x=9,16-5,84=3,32
Câu b, d bạn làm tương tự như câu a
Câu c,e bạn làm thế này, mik chỉ làm mẫu 1 câu thôi
c, x/5 = 25/30 - 13/30
x/5 = 12/30
x/5 = 2/5
x = 2/5 : 5
x = 2/5 X 1/5
x = 2/25
Vậy x=2/25
Câu e làm tương tự như vậy nhé.Bạn tính phần hiệu bên phải rồi lấy nó nhân với mẫu số của x là ra thôi.
Ủng hộ nhé
\(\dfrac{3}{4}\times\dfrac{8}{5}:1\dfrac{1}{6}\)
=\(\dfrac{6}{5}:\) \(\dfrac{7}{6}\)
=\(\dfrac{6}{5}\times\dfrac{6}{7}=\dfrac{36}{35}\)
2\(\dfrac{1}{3}\) x 1\(\dfrac{1}{4}\) -\(\dfrac{7}{5}\)
\(\dfrac{7}{3}\times\dfrac{5}{4}-\) \(\dfrac{7}{5}\)
\(\dfrac{35}{12}-\dfrac{7}{5}\)
\(\dfrac{175}{60}-\dfrac{84}{60}=\dfrac{91}{60}\)
4\(\dfrac{2}{3}+1\dfrac{1}{4} +2\dfrac{1}{3}+2\dfrac{3}{7}\)
(4 +2) + \(\left(\dfrac{2}{3}+\dfrac{1}{3}\right)\) +1\(\dfrac{1}{4}\) + \(2\dfrac{3}{7}\)
6 + 1 + \(\dfrac{5}{4}\) + \(\dfrac{17}{7}\)
7 + \(\dfrac{103}{28}\)
\(\dfrac{299}{28}\)
Câu b:
\(\frac{21}{8}:\frac{5}{6}+\frac{1}{2}:\frac{5}{6}\)
= \(\frac{63}{20}+\frac{3}{5}\)
= \(\frac{15}{4}\)
\(\left(\frac{21}{8}+\frac{1}{2}\right):\frac{5}{6}\)
\(\frac{25}{8}:\frac{5}{6}\)
\(\frac{25}{8}.\frac{6}{5}\)
\(\frac{30}{8}\)
(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_
\(\left(x-21.13\right):11=30\)
\(\left(x-273\right):11=30\)
\(\left(x-273\right)=30.11=330\)
\(x=330+273\)
\(x=603\)
\(\frac{x+9}{13-x}=\frac{6}{5}\)
\(\Rightarrow\orbr{\begin{cases}x+9=6\\13-x=5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-3\\x=8\end{cases}}\)
\(\frac{120-x}{30}=3\frac{1}{2}\)
\(\Rightarrow\frac{120-x}{30}=\frac{7}{2}\)
\(\Rightarrow\frac{120-x}{30}=\frac{105}{30}\)
\(\Rightarrow120-x=105\)
\(\Rightarrow x=120-105\)
\(\Rightarrow x=15\)