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HN
28 tháng 8 2021
a,
\(5^{x+4}-3.5^{x+3}=2.5^{11}\)
\(\Rightarrow5^{x+3}\left(5-3\right)=2.5^{11}\)
\(\Rightarrow5^{x+3}2=2.5^{11}\)
\(\Rightarrow5^{x+3}=5^{11}\)
\(\Rightarrow x+3=11\)
\(\Rightarrow x=8\)
HN
28 tháng 8 2021
b, (Check lai xem de sai o dau khong nhe)
\(3.5^{x+2}+4.5^{x+3}=19.5^{10}\)
Dat 5x ra ben ngoai
\(\Rightarrow5^x.5^23+5^x:5^{-3}.4\)
\(\Rightarrow5^x\left(5^2.3+5^{-3}.4\right)\)
\(\Rightarrow5^x\left(5^{-3}.5^5.3+5^{-3}.4\right)\)
\(\Rightarrow5^x[5^{-3}\left(5^53+4\right)\)
\(\Rightarrow5^x[5^{-3}\left(3125.3+4\right)\)
\(\Rightarrow5^x\left(5^{-3}\right).9379\)
=> Khong tim duoc gia tri cua x \(\Rightarrow x\in\varnothing\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
27 tháng 9 2024
Bài 1:
a; \(\dfrac{7}{8}\) + \(x\) = \(\dfrac{4}{7}\)
\(x\) = \(\dfrac{4}{7}\) - \(\dfrac{7}{8}\)
\(x\) = \(\dfrac{32}{56}\) - \(\dfrac{49}{56}\)
\(x=-\) \(\dfrac{49}{56}\)
Vậy \(x=-\dfrac{49}{56}\)
b; 6 - \(x\) = - \(\dfrac{3}{4}\)
\(x\) = 6 + \(\dfrac{3}{4}\)
\(x\) = \(\dfrac{24}{4}+\dfrac{3}{4}\)
\(x=\dfrac{27}{4}\)
Vậy \(x=\dfrac{27}{4}\)
c; \(\dfrac{1}{-5}\) + \(x\) = \(\dfrac{3}{4}\)
\(x\) = \(\dfrac{3}{4}\) + \(\dfrac{1}{5}\)
\(x=\dfrac{15}{20}\) + \(\dfrac{4}{20}\)
\(x=\dfrac{19}{20}\)
Vậy \(x=\dfrac{19}{20}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
27 tháng 9 2024
Bài 1:
d; - 6 - \(x\) = - \(\dfrac{3}{5}\)
\(x\) = - 6 + \(\dfrac{3}{5}\)
\(x=-\dfrac{30}{5}\) + \(\dfrac{3}{5}\)
\(x=-\dfrac{27}{5}\)
Vậy \(x=-\dfrac{27}{5}\)
e; - \(\dfrac{2}{6}\) + \(x\) = \(\dfrac{5}{7}\)
\(x\) = \(\dfrac{5}{7}\) + \(\dfrac{2}{6}\)
\(x\) = \(\dfrac{15}{21}\) + \(\dfrac{1}{3}\)
\(x=\dfrac{15}{21}\) + \(\dfrac{7}{21}\)
\(x=\dfrac{22}{21}\)
Vậy \(x=\dfrac{22}{21}\)
f; - 8 - \(x\) = - \(\dfrac{5}{3}\)
\(x\) = \(-\dfrac{5}{3}\) + 8
\(x\) = \(\dfrac{-5}{3}\) + \(\dfrac{24}{3}\)
\(x\) = \(\dfrac{-19}{3}\)
Vậy \(x=-\dfrac{19}{3}\)
JM
0
HD
2
27 tháng 6 2017
A)\(\left(4-\frac{8}{3}\right)x\frac{15}{7}-\frac{8}{5}:\frac{1}{10}\)
\(=\frac{4}{3}x\frac{15}{7}-\frac{8}{5}x\frac{1}{10}\)
\(=\frac{20}{7}-\frac{4}{25}\)
\(=\frac{222}{185}\)
B)\(\frac{7}{5}x\frac{3}{8}+\frac{7}{5}x\frac{5}{8}-\frac{37}{5}\)
\(=\frac{7}{5}x\left(\frac{3}{8}+\frac{5}{8}\right)-\frac{37}{5}\)
\(=\frac{7}{5}x1-\frac{37}{5}\)
\(=\frac{7}{5}-\frac{37}{5}\)
\(=\frac{-30}{5}
\)
\(=-6\)
LA
27 tháng 6 2017
A =\(\left(4-\frac{8}{3}\right).\frac{15}{7}-\frac{8}{5}:\frac{1}{10}\)
\(=\frac{4}{3}.\frac{15}{7}-16\)
\(=\frac{20}{7}-\frac{112}{7}\)
\(=\frac{-92}{7}\)
B\(=\frac{7}{5}.\frac{3}{8}+\frac{7}{5}.\frac{5}{8}-\frac{37}{5}\)
\(=\frac{7}{5}.\left(\frac{3}{8}+\frac{5}{8}\right)-\frac{37}{5}\)
\(=\frac{7}{5}-\frac{37}{5}\)
\(=-6\)
17 tháng 2 2020
\(/x-\frac{1}{2}/=\frac{1}{3}\\ =>\orbr{\begin{cases}x-\frac{1}{2}=\frac{1}{3}\\x-\frac{1}{2}=-\frac{1}{3}\end{cases}}\\ =>\orbr{\begin{cases}x=\frac{1}{3}+\frac{1}{2}\\x=-\frac{1}{3}+\frac{1}{2}\end{cases}}\\ =>\orbr{\begin{cases}x=\frac{5}{6}\\x=\frac{1}{6}\end{cases}}\)
17 tháng 2 2020
\(a,|x-\frac{1}{2}|=\frac{1}{3}\)
\(\Rightarrow\orbr{\begin{cases}x-\frac{1}{2}=\frac{1}{3}\\x-\frac{1}{2}=-\frac{1}{3}\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{5}{6}\\x=\frac{1}{6}\end{cases}}}\)
\(b,\frac{14}{15}:\frac{9}{10}=x:\frac{3}{7}\)
\(\frac{28}{27}=x:\frac{3}{7}\)
\(x=\frac{4}{9}\)
S
12 tháng 7 2018
a, \(\frac{x+1}{5}=\frac{3}{7}\Rightarrow7\left(x+1\right)=15\Rightarrow7x+7=15\Rightarrow7x=8\Rightarrow x=\frac{8}{7}\)
b, \(\frac{x-2}{3}=\frac{3}{8}\Rightarrow8\left(x-2\right)=9\Rightarrow8x-16=9\Rightarrow8x=25\Rightarrow x=\frac{25}{8}\)
c, \(\frac{-x-1}{2}=\frac{-3}{5}\Rightarrow5\left(-x-1\right)=-6\Rightarrow-5x-5=-6\Rightarrow-5x=-1\Rightarrow x=\frac{1}{5}\)
d, \(\frac{4}{5-x}=\frac{1}{3}\Rightarrow5-x=12\Rightarrow x=-7\)
e, \(2x\left(x-\frac{1}{7}\right)=0\Rightarrow\orbr{\begin{cases}2x=0\\x-\frac{1}{7}=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{7}\end{cases}}}\)
\(\left(\frac{-7}{4}:\frac{5}{8}\right)\cdot\frac{11}{16}=\frac{-7}{4}\cdot\frac{8}{5}\cdot\frac{11}{16}=\frac{-7.11}{4.5.2}=\frac{-77}{40}\)
5 tháng 8 2021
b) Ta có: \(5^{x+4}-3\cdot5^{x+3}=2\cdot5^{11}\)
\(\Leftrightarrow2\cdot5^{x+3}=2\cdot5^{11}\)
\(\Leftrightarrow x+3=11\)
hay x=8
c) Ta có: \(2\cdot3^{x+2}+4\cdot3^{x+1}=10\cdot3^6\)
\(\Leftrightarrow18\cdot3^x+12\cdot3^x=10\cdot3^6\)
\(\Leftrightarrow30\cdot3^x=30\cdot3^5\)
Suy ra: x=5
d) Ta có: \(6\cdot8^{x-1}+8^{x+1}=6\cdot8^{19}+8^{21}\)
\(\Leftrightarrow6\cdot\dfrac{8^x}{8}+8^x\cdot8=6\cdot8^{19}+64\cdot8^{19}\)
\(\Leftrightarrow8^x\cdot\dfrac{35}{4}=70\cdot8^{19}\)
\(\Leftrightarrow8^x=8^{20}\)
Suy ra: x=20
\(\dfrac{8}{5}\) x \(\dfrac{2}{3}\) + \(\dfrac{8}{5}\) x \(\dfrac{1}{3}\) - \(\dfrac{8}{5}\)
= \(\dfrac{8}{5}\) x (\(\dfrac{2}{3}\) + \(\dfrac{1}{3}\) - 1)
= \(\dfrac{8}{5}\) x (1 - 1)
= \(\dfrac{8}{5}\) x 0
= 0