{$4x$4x$+3y$+3y$=21$=21$4x$4x$-5y$−5y$=29$=29Nghiệm...
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| { | $4x$4x | $+3y$+3y | $=21$=21 |
| $4x$4x | $-5y$−5y | $=29$=29 |
| { | $x=$x= | ||
| $y=$y= |
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TM
0
Những câu hỏi liên quan
20 tháng 9 2021
\(a,\left\{{}\begin{matrix}3x-y=5\\4x+2y=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-y=5\\2x+y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\\ b,\left\{{}\begin{matrix}5x+2y=9\\x+5y=11\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x+2y=9\\5x+25y=55\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x+2y=9\\23y=46\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=2\end{matrix}\right.\)
\(c,\left\{{}\begin{matrix}3x+y=10\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}9x+3y=30\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}13x=39\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=1\end{matrix}\right.\\ d,\left\{{}\begin{matrix}4x+3y=22\\5x+3y=26\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\5x+3y=26\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\y=2\end{matrix}\right.\)
\(e,\left\{{}\begin{matrix}4x-3y=5\\5x+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}9x=18\\5x+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
HP
20 tháng 9 2021
a. \(\left\{{}\begin{matrix}3x-y=5\\4x+2y=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}6x-2y=10\\4x+2y=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}10x=20\\6x-2y=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
b. \(\left\{{}\begin{matrix}5x+2y=9\\x+5y=11\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x+2y=9\\5x+25y=55\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}23y=46\\5x+2y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=2\\x=1\end{matrix}\right.\)
c. \(\left\{{}\begin{matrix}3x+y=10\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}9x+3y=30\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}13x=39\\4x-3y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=1\end{matrix}\right.\)
d. \(\left\{{}\begin{matrix}4x+3y=22\\5x+3y=26\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\4x+3y=22\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\y=2\end{matrix}\right.\)
e. \(\left\{{}\begin{matrix}4x-3y=5\\5x+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}9x=18\\4x-3y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
HT
2
17 tháng 9 2017
\(\frac{4x-3}{3}=\frac{3y+1}{7}=\frac{4x+3y-2}{5y}\)
\(=\frac{4x-3+3y+1-\left(4x+3y-2\right)}{3+7-5y}\)
\(=\frac{4x-3+3y+1-4x-3y+2}{10-5y}\)
\(=\frac{\left(4x-4x\right)+3y-3y-3+1+2}{10-5y}=0\)
\(\Rightarrow\hept{\begin{cases}4x-3=0\Leftrightarrow x=\frac{3}{4}\\3y+1=0\Leftrightarrow y=-\frac{1}{3}\end{cases}}\)
Vậy \(x=\frac{3}{4};y=-\frac{1}{3}\).
T
24 tháng 8 2023
\(x^2-y^2+5x-5y\)
\(=\left(x-y\right)\left(x+y\right)+5\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y+5\right)\)
\(---\)
\(x^2-16y^2+4x+4\)
\(=\left(x^2+4x+4\right)-16y^2\)
\(=\left(x+2\right)^2-\left(4y\right)^2\)
\(=\left(x+2-4y\right)\left(x+2+4y\right)\)
\(=\left(x-4y+2\right)\left(x+4y+2\right)\)
\(---\)
\(3x^2+6xy+3y^2-12\)
\(=3\left(x^2+2xy+y^2-4\right)\)
\(=3\left[\left(x+y\right)^2-2^2\right]\)
\(=3\left(x+y-2\right)\left(x+y+2\right)\)
\(---\)
\(4x^3+4x^2+x\)
\(=x\left(4x^2+4x+1\right)\)
\(=x\left(2x+1\right)^2\)
PH
1
H9
HT.Phong (9A5)
CTVHS
3 tháng 7 2023
a) \(\left\{{}\begin{matrix}2x+3y=5\\4x-5y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}4x+6y=10\\4x-5y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+3y=5\\11y=9\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+3\cdot\dfrac{9}{11}=5\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+\dfrac{27}{11}=5\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x=\dfrac{28}{11}\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{14}{11}\\y=\dfrac{9}{11}\end{matrix}\right.\)
Vậy: \(x=\dfrac{14}{11};y=\dfrac{9}{11}\)
NB
1
LB
6 tháng 10 2018
\(\dfrac{4x-3y}{5}=\dfrac{5y-4z}{6}=\dfrac{-4x-2y+4z}{7}=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{4x-3y}{5}=0\Leftrightarrow x=\dfrac{3y}{4}\\\dfrac{5y-4z}{6}=0\Leftrightarrow z=\dfrac{5y}{4}\end{matrix}\right.\)
Ta có \(x+y+z=36\)
\(\Leftrightarrow\dfrac{3y}{4}+y+\dfrac{5y}{4}=36\)
\(\Rightarrow y=12\)
\(\Rightarrow\left\{{}\begin{matrix}x=9\\z=15\end{matrix}\right.\)
theer
8 tháng 11 2015
4x=3y=>x/3=y/4=>x/9=y/12 (1)
5y=3z=>y/3=z/5=>y/12=z/20 (2)
từ 1 và 2 ta có :
x/9=y/12=z/20
=>2x/18=3y/36
áp ...ta có :
2x/18=3y/36=2x-3y/18-36=6/-18=-1/3
=>x/9=-1/3=>x=-3
=>y/12=-1/3=>y=-4
=>z/20=-1/3=>z=-20/3
8 tháng 11 2015
\(\Rightarrow\frac{x}{3}=\frac{y}{4};\frac{y}{3}=\frac{z}{5}\Rightarrow\frac{x}{9}=\frac{y}{12}=\frac{z}{20}=\frac{2x-3y}{2.9-3.12}=\frac{6}{-18}=-\frac{1}{3}\)
x =-1/3 . 9 = -3
y= -1/3 .12 = -4
z = -1/3 .20 = -20/3
H9
HT.Phong (9A5)
CTVHS
7 tháng 8 2023
a) Ta có: \(3x-y=13\) và \(2x-4y=60\)
Mà: \(2\left(x+2y\right)=60\Rightarrow x+2y=30\) (1)
Và: \(3x-y=13\Rightarrow6x-2y=26\) (2)
Cộng (1) với (2) theo vế ta có:
\(\left(x+6x\right)+\left(-2y+2y\right)=30+26\)
\(\Rightarrow7x=56\)
\(\Rightarrow x=8\)
Ta tìm được y:
\(8+2y=30\)
\(\Rightarrow2y=22\)
\(\Rightarrow y=11\)