\(\left\{{}\begin{matrix}3x+y=3\\2x-y=7\end{matrix}\right.\)
..
\(\left\{{}\begin{matrix}2x+5y=8\\2x-3y=0\end{matrix}\right.\)
..
\(\left\{{}\begin{matrix}4x+3y=6\\2x+y=4\end{matrix}\right.\)
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giải hpt bằng phương pháp thế:9) left{{}begin{matrix}3x-2y2x+3y6end{matrix}right.10) left{{}begin{matrix}2x+3y24x-y-10end{matrix}right.11) left{{}begin{matrix}3x-2y32x-dfrac{4}{3}y1end{matrix}right.12) left{{}begin{matrix}5x+y32x+0,4y1,2end{matrix}right.giúp mk vs ạ mai mk học rồi
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giải hpt bằng phương pháp thế:
9) \(\left\{{}\begin{matrix}3x-2=y\\2x+3y=6\end{matrix}\right.\)
10) \(\left\{{}\begin{matrix}2x+3y=2\\4x-y-1=0\end{matrix}\right.\)
11) \(\left\{{}\begin{matrix}3x-2y=3\\2x-\dfrac{4}{3}y=1\end{matrix}\right.\)
12) \(\left\{{}\begin{matrix}5x+y=3\\2x+0,4y=1,2\end{matrix}\right.\)
giúp mk vs ạ mai mk học rồi
9: \(\left\{{}\begin{matrix}3x-2=y\\2x+3y=6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-y=2\\2x+3y=6\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}6x-2y=4\\6x+9y=18\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-11y=-14\\3x-y=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{14}{11}\\x=\dfrac{y+2}{3}=\dfrac{\dfrac{14}{11}+2}{3}=\dfrac{12}{11}\end{matrix}\right.\)
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\(9,\Leftrightarrow\left\{{}\begin{matrix}3x-2=y\\2x+3\left(3x-2\right)=6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-2=y\\11x=12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{12}{11}\\y=\dfrac{14}{11}\end{matrix}\right.\)
\(10,\Leftrightarrow\left\{{}\begin{matrix}2x=2-3y\\2\left(2-3y\right)-y-1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x=2-3y\\4-6y-y-1=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{5}{14}\\y=\dfrac{3}{7}\end{matrix}\right.\)
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giai hpt
a.\(\left\{{}\begin{matrix}x=y+4\\2x+3=0\end{matrix}\right.\)
b.\(\left\{{}\begin{matrix}2x+y=7\\3y-x=7\end{matrix}\right.\)
c.\(\left\{{}\begin{matrix}5x+y=3\\-x-\dfrac{1}{5}y=\dfrac{-3}{5}\end{matrix}\right.\)
d.\(\left\{{}\begin{matrix}3x-5y=-18\\x-5=2y\end{matrix}\right.\)
\(a) \begin{cases}x=y+4\\2x+3=0\end{cases}\Leftrightarrow\begin{cases}x = y + 4\\2x = -3\end{cases}\Leftrightarrow\begin{cases}\dfrac{-3}{2} = y + 4\\x = \dfrac{-3}{2}\end{cases}\Leftrightarrow\begin{cases}y = \dfrac{-11}{2}\\x = \dfrac{-3}{2}\end{cases}\\b) \begin{cases}2x + y = 7\\3y - x = 7\end{cases}\Leftrightarrow\begin{cases}2x + y = 7\\6y - 2x = 14\end{cases}\Leftrightarrow\begin{cases}2x + y = 7\\7y = 21\end{cases}\Leftrightarrow\begin{cases}2x + 3 = 7\\y = 3\end{cases}\Leftrightarrow\begin{cases}x=2\\y=3\end{cases}\\ c) \begin{cases} 5x + y = 3 \\ -x - \dfrac{1}{5}y=\dfrac{-3}{5} \end{cases} \Leftrightarrow \begin{cases} 5x + y = 3 \\ 5x + y = 3 \end{cases} (luôn\ đúng) \Leftrightarrow Phương\ trình\ vô\ số\ nghiệm \\d) \begin{cases} 3x - 5y = -18 \\ x - 5 = 2y \end{cases} \Leftrightarrow \begin{cases} 3x - 5y = -18 \\ 3x - 6y = 15 \end{cases} \Leftrightarrow \begin{cases} x - 5 = 2.(-33)\\ y = -13 \end{cases} \Leftrightarrow \begin{cases}x = -61\\y=-33 \end{cases} \)
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Giải phương trình bằng phương pháp thế :
1) left{{}begin{matrix}4x+y28x+3y5end{matrix}right.
2) left{{}begin{matrix}x-ym2x+y4end{matrix}right.
3)left{{}begin{matrix}3x+2y6x-y2end{matrix}right.
4) left{{}begin{matrix}2x-3y1-4x+6y2end{matrix}right.
5)left{{}begin{matrix}2x+3y55x-4y1end{matrix}right.
6)left{{}begin{matrix}3x-y7x+2y0end{matrix}right.
7)left{{}begin{matrix}x+4y23x+2y4end{matrix}right.
8)left{{}begin{matrix}-x-y2-2x-3y9end{matrix}right.
9)left{{...
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Giải phương trình bằng phương pháp thế :
1) \(\left\{{}\begin{matrix}4x+y=2\\8x+3y=5\end{matrix}\right.\)
2) \(\left\{{}\begin{matrix}x-y=m\\2x+y=4\end{matrix}\right.\)
3)\(\left\{{}\begin{matrix}3x+2y=6\\x-y=2\end{matrix}\right.\)
4) \(\left\{{}\begin{matrix}2x-3y=1\\-4x+6y=2\end{matrix}\right.\)
5)\(\left\{{}\begin{matrix}2x+3y=5\\5x-4y=1\end{matrix}\right.\)
6)\(\left\{{}\begin{matrix}3x-y=7\\x+2y=0\end{matrix}\right.\)
7)\(\left\{{}\begin{matrix}x+4y=2\\3x+2y=4\end{matrix}\right.\)
8)\(\left\{{}\begin{matrix}-x-y=2\\-2x-3y=9\end{matrix}\right.\)
9)\(\left\{{}\begin{matrix}2x-3y=2\\-4x+6y=2\end{matrix}\right.\)
giúp mình với :((
1) \(\left\{{}\begin{matrix}4x+y=2\\8x+3y=5\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}y=2-4x\\8x+3\left(2-4x\right)=5\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{1}{4}\\y=1\end{matrix}\right.\)
2) 2 pt 3 ẩn không giải được.
3) \(\left\{{}\begin{matrix}3x+2y=6\\x-y=2\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=x-2\\3x+2\left(x-2\right)=6\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=0\end{matrix}\right.\)
4) \(\left\{{}\begin{matrix}2x-3y=1\\-4x+6y=2\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{3y+1}{2}\\-4\cdot\frac{3y+1}{2}+6y=2\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=\varnothing\\x=\varnothing\end{matrix}\right.\)
5) \(\left\{{}\begin{matrix}2x+3y=5\\5x-4y=1\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{-3y+5}{2}\\5\cdot\frac{-3y+5}{2}-4y=1\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=1\\x=1\end{matrix}\right.\)
6) \(\left\{{}\begin{matrix}3x-y=7\\x+2y=0\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=3x-7\\x+2\left(3x-7\right)=0\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=-1\end{matrix}\right.\)
7) \(\left\{{}\begin{matrix}x+4y=2\\3x+2y=4\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=2-4y\\3\left(2-4y\right)+2y=4\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=\frac{1}{5}\\x=\frac{6}{5}\end{matrix}\right.\)
8) \(\left\{{}\begin{matrix}-x-y=2\\-2x-3y=9\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=-x-2\\-2x-3\left(-x-2\right)=9\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=-5\end{matrix}\right.\)
9) \(\left\{{}\begin{matrix}2x-3y=2\\-4x+6y=2\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{3y+2}{2}\\-4\cdot\frac{3y+2}{2}+6y=2\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=\varnothing\\x=\varnothing\end{matrix}\right.\)
Giải phương trình:
1. \(\left\{{}\begin{matrix}4x-2y=3\\6x-3y=5\end{matrix}\right.\)
2. \(\left\{{}\begin{matrix}2x-3y=5\\4x+6y=10\end{matrix}\right.\)
3. \(\left\{{}\begin{matrix}3x-4y+2=0\\5x+2y=14\end{matrix}\right.\)
4. \(\left\{{}\begin{matrix}2x+5y=3\\3x-2y=14\end{matrix}\right.\)
1) \(\left\{{}\begin{matrix}3x-2y=4\\4x+2y=10\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}3x-2y=4\\7x=14\end{matrix}\right.< =>\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
2)\(\left\{{}\begin{matrix}2x+3y=5\\4x+6y=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x+6y=10\\4x=6y=10\end{matrix}\right.\)
=> Hệ có vô số nghiệm.
3)\(\left\{{}\begin{matrix}3x-4y=-2\\10x+4y=28\end{matrix}\right.\)
<=>\(\left\{{}\begin{matrix}3x-4y=-2\\13x=26\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=2\end{matrix}\right.\)
4)\(\left\{{}\begin{matrix}6x+15y=9\\6x-4y=28\end{matrix}\right.\)
<=>\(\left\{{}\begin{matrix}6x+15y=9\\19y=19\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\y=-1\end{matrix}\right.\)
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giải hệ pt sau
aleft{{}begin{matrix}4x+y28x+3y5end{matrix}right. bleft{{}begin{matrix}3x_{ }-2y114x-5y3end{matrix}right. cleft{{}begin{matrix}4x+3y135x-3y_{ }-31end{matrix}right. Dleft{{}begin{matrix}7X+5Y193x+5y31end{matrix}right.
eleft{{}begin{matrix}7x-5y33x+10y62end{matrix}right. fleft{{}begin{matrix}2x+5y113x+2y11end{matrix}right. gleft{{}begin{matrix}x+3y4y-x+52x-y3x-...
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giải hệ pt sau
a\(\left\{{}\begin{matrix}4x+y=2\\8x+3y=5\end{matrix}\right.\) b\(\left\{{}\begin{matrix}3x_{ }-2y=11\\4x-5y=3\end{matrix}\right.\) c\(\left\{{}\begin{matrix}4x+3y=13\\5x-3y=_{ }-31\end{matrix}\right.\) D\(\left\{{}\begin{matrix}7X+5Y=19\\3x+5y=31\end{matrix}\right.\)
e\(\left\{{}\begin{matrix}7x-5y=3\\3x+10y=62\end{matrix}\right.\) f\(\left\{{}\begin{matrix}2x+5y=11\\3x+2y=11\end{matrix}\right.\) g\(\left\{{}\begin{matrix}x+3y=4y-x+5\\2x-y=3x-2\left(y+1\right)\end{matrix}\right.\)
a)\(\left\{{}\begin{matrix}8x+2y=4\\8x+3y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=1\\4x+1=2\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}y=1\\x=\frac{1}{4}\end{matrix}\right.\)b)
\(\left\{{}\begin{matrix}12x-8y=44\\12x-15y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}7y=35\\4x-5y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=5\\4x-5.5=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=5\\x=7\end{matrix}\right.\)c)\(\left\{{}\begin{matrix}9x=-18\\4x+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\4.\left(-2\right)+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=7\end{matrix}\right.\)
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Giải phương trình:
1. \(\left\{{}\begin{matrix}5x-2y=-9\\4x+3y=2\end{matrix}\right.\)
2. \(\left\{{}\begin{matrix}2x+y-4=0\\x+2y-5=0\end{matrix}\right.\)
3. \(\left\{{}\begin{matrix}2x+3y-7=0\\x+2y-4=0\end{matrix}\right.\)
4. \(\left\{{}\begin{matrix}5x+6y=17\\9x-y=7\end{matrix}\right.\)
1)
HPT \(\Leftrightarrow\left\{{}\begin{matrix}15x-6y=-27\\8x+6y=4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}2y=5x+9\\23x=-23\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-1\\y=2\end{matrix}\right.\)
Vậy \(\left(x;y\right)=\left(-1;2\right)\)
2)
HPT \(\Leftrightarrow\left\{{}\begin{matrix}2x+y=4\\2x+4y=10\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}-3y=-6\\x=5-2y\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}y=2\\x=1\end{matrix}\right.\)
Vậy \(\left(x;y\right)=\left(1;2\right)\)
3)
HPT \(\Leftrightarrow\left\{{}\begin{matrix}4x+6y=14\\3x+6y=12\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2\\2y=4-x\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=1\end{matrix}\right.\)
Vậy \(\left(x;y\right)=\left(2;1\right)\)
4)
HPT \(\Leftrightarrow\left\{{}\begin{matrix}5x+6y=17\\54x-6y=42\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}59x=59\\y=9x-7\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=2\end{matrix}\right.\)
Vậy \(\left(x;y\right)=\left(1;2\right)\)
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Giải các hệ phương trình sau bằng phương pháp cộng đại số:a) left{{}begin{matrix}3x+y32x-y7end{matrix}right.; b) left{{}begin{matrix}2x+5y82x-3y0end{matrix}right.; c) left{{}begin{matrix}4x+3y62x+y4end{matrix}right.;d) left{{}begin{matrix}2x+3y-23x-2y-3end{matrix}right.; e) left{{}begin{matrix}0,3x+0,5y31,5x-2y1,5end{matrix}right..
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Giải các hệ phương trình sau bằng phương pháp cộng đại số:
a) \(\left\{{}\begin{matrix}3x+y=3\\2x-y=7\end{matrix}\right.;\)
b) \(\left\{{}\begin{matrix}2x+5y=8\\2x-3y=0\end{matrix}\right.;\)
c) \(\left\{{}\begin{matrix}4x+3y=6\\2x+y=4\end{matrix}\right.;\)
d) \(\left\{{}\begin{matrix}2x+3y=-2\\3x-2y=-3\end{matrix}\right.;\)
e) \(\left\{{}\begin{matrix}0,3x+0,5y=3\\1,5x-2y=1,5\end{matrix}\right..\)
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Giải hệ phương trình sau bằng phương pháp thế
1) \(\left\{{}\begin{matrix}x-2y=4\\-2x+5y=-3\end{matrix}\right.\)
2) \(\left\{{}\begin{matrix}2x+y=10\\5x-3y=3\end{matrix}\right.\)
3) \(\left\{{}\begin{matrix}x+2y=4\\-3x+y=7\end{matrix}\right.\)
\(1,\Leftrightarrow\left\{{}\begin{matrix}x=2y+4\\-4y-8+5y=-3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\cdot5+4=14\\y=5\end{matrix}\right.\\ 2,\Leftrightarrow\left\{{}\begin{matrix}5x-30+6x=3\\y=10-2x\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=4\end{matrix}\right.\\ 3,\Leftrightarrow\left\{{}\begin{matrix}x=4-2y\\6y-12+y=7\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-\dfrac{10}{7}\\y=\dfrac{19}{7}\end{matrix}\right.\)
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a) left{{}begin{matrix}2x+5y33x-2y-8end{matrix}right.
b) left{{}begin{matrix}x+3y52x-5y-1end{matrix}right.
c) left{{}begin{matrix}3x-4y182x+y1end{matrix}right.
d)left{{}begin{matrix}x-2y+z122x-y+3z18-3x+3y+3z-9end{matrix}right.
e) left{{}begin{matrix}x-2y+4z13y-3z-77z14end{matrix}right.
f) left{{}begin{matrix}2x+y+3z2-x+4y-6z55x-y+3z-5end{matrix}right.
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a) \(\left\{{}\begin{matrix}2x+5y=3\\3x-2y=-8\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}x+3y=5\\2x-5y=-1\end{matrix}\right.\)
c) \(\left\{{}\begin{matrix}3x-4y=18\\2x+y=1\end{matrix}\right.\)
d)\(\left\{{}\begin{matrix}x-2y+z=12\\2x-y+3z=18\\-3x+3y+3z=-9\end{matrix}\right.\)
e) \(\left\{{}\begin{matrix}x-2y+4z=13\\y-3z=-7\\7z=14\end{matrix}\right.\)
f) \(\left\{{}\begin{matrix}2x+y+3z=2\\-x+4y-6z=5\\5x-y+3z=-5\end{matrix}\right.\)
a: \(\Leftrightarrow\left\{{}\begin{matrix}4x+10y=6\\15x-10y=-40\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-\dfrac{34}{19}\\y=\dfrac{25}{19}\end{matrix}\right.\)
b: x+3y=5 và 2x-5y=-1
=>2x+6y=10 và 2x-5y=-1
=>11y=11 và x+3y=5
=>y=1 và x=2
c: 3x-4y=18 và 2x+y=1
=>3x-4y=18 và 8x+4y=4
=>11x=22 và 2x+y=1
=>x=2 và y=1-2*2=-3
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