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TC
2
S
20 tháng 2 2021
a, \(\dfrac{6}{x-3}=\dfrac{9}{2x-7}\)
=> 6(2x-7) = 9(x-3)
=> 12x - 42 = 9x - 27
=> 12x - 9x = -27 + 42
=> 3x = 15
=> x = 5
Vậy x = 5
b, \(\dfrac{-7}{x+1}=\dfrac{6}{x+27}\)
=> -7(x + 27) = 6(x + 1)
=> -7x - 189 = 6x + 6
=> -7x - 6x = 6 + 189
=> -13x = 195
=> x = -15
Vậy x = -15
20 tháng 2 2021
a) Ta có: \(\dfrac{6}{x-3}=\dfrac{9}{2x-7}\)
\(\Leftrightarrow6\left(2x-7\right)=9\left(x-3\right)\)
\(\Leftrightarrow12x-42=9x-27\)
\(\Leftrightarrow12x-9x=-27+42\)
\(\Leftrightarrow3x=15\)
hay x=5
Vậy: x=5
b) Ta có: \(\dfrac{-7}{x+1}=\dfrac{6}{x+27}\)
\(\Leftrightarrow6\left(x+1\right)=-7\left(x+27\right)\)
\(\Leftrightarrow6x+6=-7x+189\)
\(\Leftrightarrow6x+7x=189-6\)
\(\Leftrightarrow13x=183\)
hay \(x=\dfrac{183}{13}\)
Vậy: \(x=\dfrac{183}{13}\)
9 tháng 5 2021
Giải:
a) \(\dfrac{12}{16}=\dfrac{-x}{4}=\dfrac{21}{y}=\dfrac{z}{80}\)
\(\Rightarrow x=\dfrac{12.-4}{16}=-3\)
\(\Rightarrow y=\dfrac{16.21}{12}=28\)
\(\Rightarrow z=\dfrac{12.80}{16}=60\)
b) \(\dfrac{1}{3}x+\dfrac{2}{5}\left(x-1\right)\) =0
\(\dfrac{1}{3}x+\dfrac{2}{5}x-\dfrac{2}{5}=0\)
\(x.\left(\dfrac{1}{3}+\dfrac{2}{5}\right)\) \(=0+\dfrac{2}{5}\)
\(x.\dfrac{11}{15}\) \(=\dfrac{2}{5}\)
x \(=\dfrac{2}{5}:\dfrac{11}{15}\)
x \(=\dfrac{6}{11}\)
c) (2x-3)(6-2x)=0
⇒2x-3=0 hoặc 6-2x=0
x=3/2 hoặc x=3
d) \(\dfrac{-2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}\)
\(\dfrac{1}{3}\left(2x-5\right)=\dfrac{-2}{3}-\dfrac{3}{2}\)
\(\dfrac{1}{3}\left(2x-5\right)=\dfrac{-13}{6}\)
\(2x-5=\dfrac{-13}{6}:\dfrac{1}{3}\)
\(2x-5=\dfrac{-13}{2}\)
\(2x=\dfrac{-13}{2}+5\)
\(2x=\dfrac{-3}{2}\)
\(x=\dfrac{-3}{2}:2\)
\(x=\dfrac{-3}{4}\)
e) \(2\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{1}{4}\)
\(\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{1}{4}:2\)
\(\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{1}{8}\)
\(\Rightarrow\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{1}{8}\) hoặc \(\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{-1}{8}\)
\(x=\dfrac{11}{12}\) hoặc \(x=\dfrac{5}{12}\)
L
19 tháng 5 2022
a) (2x - 3)(6 - 2x) = 0
=> \(\left[{}\begin{matrix}2x-3=0\\6-2x=0\end{matrix}\right.=>\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)
b) \(5\dfrac{4}{7}:x=13=>\dfrac{39}{7}:x=13=>x=\dfrac{39}{7}:13=>x=\dfrac{3}{7}\)
c) \(2x-\dfrac{3}{7}=6\dfrac{2}{7}=>2x-\dfrac{3}{7}=\dfrac{44}{7}=>2x=\dfrac{47}{7}=>x=\dfrac{47}{14}\)
d) \(\dfrac{x}{5}+\dfrac{1}{2}=\dfrac{6}{10}=>\dfrac{x}{5}=\dfrac{6}{10}-\dfrac{1}{2}=>\dfrac{x}{5}=\dfrac{1}{10}=>x.10=5=>x=\dfrac{1}{2}\)
e) \(\dfrac{x+3}{15}=\dfrac{1}{3}=>\left(x+3\right).3=15=>x+3=5=>x=2\)
8 tháng 7 2021
1) PT \(\Leftrightarrow\dfrac{x+3}{15}=\dfrac{4}{15}\) \(\Rightarrow x+3=4\) \(\Rightarrow x=1\)
Vậy ...
2) Mạnh dạn đoán đề là \(\left(2x-5\right)\left(x-3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2x-5=0\\x-3=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=3\end{matrix}\right.\)
Vậy ...
3) PT \(\Rightarrow3x-4-2x+5=3\)
\(\Rightarrow x=2\)
Vậy ...
4) PT \(\Rightarrow\left[{}\begin{matrix}2x+1=0\\\dfrac{1}{2}x-1=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=2\end{matrix}\right.\)
Vậy ...
8 tháng 7 2021
3) Ta có: \(\left(3x-4\right)-\left(2x-5\right)=3\)
\(\Leftrightarrow3x-4-2x+5=3\)
\(\Leftrightarrow x+1=3\)
hay x=2
AH
Akai Haruma
Giáo viên
25 tháng 2 2021
Lời giải:
a)
$3^{2x+1}.7^y=9.21^x=3^2.(3.7)^x=3^{2+x}.7^x$
Vì $x,y$ là số tự nhiên nên suy ra $2x+1=2+x$ và $y=x$
$\Rightarrow x=y=1$
b) \(\frac{27^x}{3^{2x-y}}=\frac{3^{3x}}{3^{2x-y}}=3^{x+y}=243=3^5\Rightarrow x+y=5(1)\)
\(\frac{25^x}{5^{x+y}}=\frac{5^{2x}}{5^{x+y}}=5^{x-y}=125=5^3\Rightarrow x-y=3\) $(2)$
Từ $(1);(2)\Rightarrow x=4; y=1$
22 tháng 6 2021
Giải:
a) \(\left(3\dfrac{1}{2}+2x\right).3\dfrac{2}{3}=5\dfrac{1}{3}\)
\(\left(\dfrac{7}{2}+2x\right).\dfrac{11}{3}=\dfrac{16}{3}\)
\(\dfrac{7}{2}+2x=\dfrac{16}{3}:\dfrac{11}{3}\)
\(\dfrac{7}{2}+2x=\dfrac{16}{11}\)
\(2x=\dfrac{16}{11}-\dfrac{7}{2}\)
\(2x=\dfrac{-45}{22}\)
\(x=\dfrac{-45}{22}:2\)
\(x=\dfrac{-45}{44}\)
b) \(3-\left(17-x\right)=-12\)
\(3-17+x=-12\)
\(x=-12-3+17\)
\(x=2\)
c) \(\dfrac{2}{3}x+\dfrac{1}{2}=\dfrac{1}{10}\)
\(\dfrac{2}{3}x=\dfrac{1}{10}-\dfrac{1}{2}\)
\(\dfrac{2}{3}x=\dfrac{-2}{5}\)
\(x=\dfrac{-2}{5}:\dfrac{2}{3}\)
\(x=\dfrac{-3}{5}\)
d) \(\dfrac{3}{4}-2.\left|2x-\dfrac{2}{3}\right|=2\)
\(2.\left|2x-\dfrac{2}{3}\right|=\dfrac{3}{4}-2\)
\(2.\left|2x-\dfrac{2}{3}\right|=\dfrac{-5}{4}\)
\(\left|2x-\dfrac{2}{3}\right|=\dfrac{-5}{4}:2\)
\(\left|2x-\dfrac{2}{3}\right|=\dfrac{-5}{8}\)
Vì giá trị tuyệt đối của 1 số nguyên ko bao giờ là số âm nên \(x\in\varnothing\)
e) \(\left(-0,6x-\dfrac{1}{2}\right).\dfrac{3}{4}-\left(-1\right)=\dfrac{1}{3}\)
\(\left(-0,6x-\dfrac{1}{2}\right).\dfrac{3}{4}=\dfrac{1}{3}+\left(-1\right)\)
\(\left(-0,6x-\dfrac{1}{2}\right).\dfrac{3}{4}=\dfrac{-2}{3}\)
\(-0,6x-\dfrac{1}{2}=\dfrac{-2}{3}:\dfrac{3}{4}\)
\(-0,6x-\dfrac{1}{2}=\dfrac{-8}{9}\)
\(-0,6x=\dfrac{-8}{9}+\dfrac{1}{2}\)
\(-0,6x=\dfrac{-7}{18}\)
\(x=\dfrac{-7}{18}:-0.6\)
\(x=\dfrac{35}{54}\)
f) \(\left(3x-1\right).\left(\dfrac{-1}{2}x+5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}3x-1=0\\\dfrac{-1}{2}x+5=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=10\end{matrix}\right.\)
g) \(60\%.x+\dfrac{2}{3}=\dfrac{1}{3}.6\dfrac{1}{3}\)
\(\dfrac{3}{5}.x+\dfrac{2}{3}=\dfrac{1}{3}.\dfrac{19}{3}\)
\(\dfrac{3}{5}.x+\dfrac{2}{3}=\dfrac{19}{9}\)
\(\dfrac{3}{5}.x=\dfrac{19}{9}-\dfrac{2}{3}\)
\(\dfrac{3}{5}.x=\dfrac{13}{9}\)
\(x=\dfrac{13}{9}:\dfrac{3}{5}\)
\(x=\dfrac{65}{27}\)
Chúc bạn học tốt!
HT
3
S
9 tháng 5 2023
\(\dfrac{2x-1}{12}=\dfrac{5}{3}\)
\(\Rightarrow\left(2x-1\right)3=12\cdot5\)
\(\Rightarrow6x-3=60\)
\(\Rightarrow6x=63\)
\(\Rightarrow x=\dfrac{21}{2}\)
\(\dfrac{2x-3}{15}=\dfrac{3}{5}\)
\(\Rightarrow\left(2x-3\right)5=15\cdot3\)
\(\Rightarrow10x-15=45\)
\(\Rightarrow10x=60\)
\(\Rightarrow x=6\)
#Đạt Đang Bận Thở
9 tháng 5 2023
\(\dfrac{2x-1}{12}=\dfrac{20}{12}\)
\(\Leftrightarrow2x-1=20\)
\(\Leftrightarrow2x=21\)
\(\Leftrightarrow x=\dfrac{21}{2}\)
b. \(\dfrac{2x-3}{15}=\dfrac{9}{15}\)
\(\Leftrightarrow2x-3=9\)
\(\Leftrightarrow x=6\)
ĐKXĐ: \(x\ne-\dfrac{1}{2}\)
\(\dfrac{2x+1}{-27}=\dfrac{-3}{2x+1}\)
\(\left(2x+1\right)^2=-3.\left(-27\right)\)
\(\left(2x+1\right)^2=81\)
\(2x+1=9\) hoặc \(2x+1=-9\)
\(x=4\) hoặc \(x=-5\)