Giải Hệ phương trình sau:
\(\left\{{}\begin{matrix}\left(\sqrt{5}+2\right)x+y=3-\sqrt{5}\\-x+2y=6-2\sqrt{5}\end{matrix}\right.\)
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Giải hệ phương trình sau bằng phương pháp thế
a)
\(\left\{{}\begin{matrix}\sqrt{5}+2)x+y=3-\sqrt{5}\\-x+2y=6-2\sqrt{5}\end{matrix}\right.\)
b)
\(\left\{{}\begin{matrix}5\left(x+2y\right)=3x-1\\2x+4=3\left(x-5y\right)-12\end{matrix}\right.\)
Giải các hệ phương trình saua,left{{}begin{matrix}sqrt{3}x-ysqrt{2}x-sqrt{2}ysqrt{3}end{matrix}right. b, left{{}begin{matrix}5left(x-yright)-3left(2x+3yright)123left(x+2yright)-4left(x+2yright)5end{matrix}right.c, left{{}begin{matrix}dfrac{x+2}{y-1}dfrac{x-4}{y+2}dfrac{2x+3}{y-1}dfrac{4x+1}{2y+1}end{matrix}right.
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Giải các hệ phương trình sau
a,\(\left\{{}\begin{matrix}\sqrt{3}x-y=\sqrt{2}\\x-\sqrt{2}y=\sqrt{3}\end{matrix}\right.\)
b, \(\left\{{}\begin{matrix}5\left(x-y\right)-3\left(2x+3y\right)=12\\3\left(x+2y\right)-4\left(x+2y\right)=5\end{matrix}\right.\)
c, \(\left\{{}\begin{matrix}\dfrac{x+2}{y-1}=\dfrac{x-4}{y+2}\\\dfrac{2x+3}{y-1}=\dfrac{4x+1}{2y+1}\end{matrix}\right.\)
\(\left\{{}\begin{matrix}\dfrac{x+2}{y-1}=\dfrac{x-4}{y+2}\\\dfrac{2x+3}{y-1}=\dfrac{4x+1}{2y+1}\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}\left(x+2\right)\left(y+2\right)=\left(y-1\right)\left(x-\text{4}\right)\\\left(2x+3\right)\left(2y+1\right)=\left(y-1\right)\left(4x+1\right)\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}xy+2x+2y+4=xy-4y-x+4\\4xy+2x+6y+3=4xy-4x+y-1\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}3x+6y=0\\6x+5y=-4\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}x=-\dfrac{8}{7}\\y=\dfrac{4}{7}\end{matrix}\right.\)(TM)
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\(\left\{{}\begin{matrix}5\left(x-y\right)-3\left(2x+3y\right)=12\\3\left(x+2y\right)-4\left(x+2y\right)=5\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}5x-5y-6x-9y=12\\3x+6y-4x-8y=5\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}-x-14y=12\\-x-2y=5\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}x=-\dfrac{26}{3}\\y=-\dfrac{7}{12}\end{matrix}\right.\)
Vậy HPT có nghiệm (x;y) = (\(-\dfrac{26}{3};-\dfrac{7}{12}\))
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giải hệ phương trình (theo 4 cách):
a/ \(\left\{{}\begin{matrix}\sqrt{5}x-y=\sqrt{5}\left(\sqrt{3}-1\right)\\2\sqrt{3}x+3\sqrt{5}y=21\end{matrix}\right.\)
b/ \(\left\{{}\begin{matrix}1,7x-2y=3,8\\2,1x+5y=0,4\end{matrix}\right.\)
a: \(\left\{{}\begin{matrix}\sqrt{5}x-y=\sqrt{5}\left(\sqrt{3}-1\right)\\2\sqrt{3}x+3\sqrt{5}y=21\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}2\sqrt{15}x-2\sqrt{3}\cdot y=2\sqrt{15}\left(\sqrt{3}-1\right)\\2\sqrt{15}x+15y=21\sqrt{5}\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}-2\sqrt{3}y-15y=2\sqrt{45}-2\sqrt{15}-21\sqrt{5}\\2\sqrt{3}x+3\sqrt{5}y=21\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y\left(-2\sqrt{3}-15\right)=-15\sqrt{5}-2\sqrt{15}\\2\sqrt{3}\cdot x+3\sqrt{5}\cdot y=21\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=\dfrac{15\sqrt{5}+2\sqrt{15}}{2\sqrt{3}+15}=\sqrt{5}\\2\sqrt{3}x+3\sqrt{5}\cdot y=21\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=\sqrt{5}\\2\sqrt{3}x=21-3\sqrt{5}\cdot\sqrt{5}=21-15=6\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}y=\sqrt{5}\\x=\dfrac{6}{2\sqrt{3}}=\sqrt{3}\end{matrix}\right.\)
b: \(\left\{{}\begin{matrix}1,7x-2y=3,8\\2,1x+5y=0,4\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}8,5x-10y=19\\4,2x+10y=0,8\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}8,5x-10y+4,2x+10y=19,8\\2,1x+5y=0,4\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}12,7x=19,8\\2,1x+5y=0,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{198}{127}\\5y=0,4-2,1x=-\dfrac{365}{127}\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x=\dfrac{198}{127}\\y=-\dfrac{73}{127}\end{matrix}\right.\)
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Giải hệ phương trình sau bằng phương pháp cộng đại số:
a) \(\left\{{}\begin{matrix}-x+2y=3\\3x+y=-1\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}2x+2\sqrt{3}y=1\\\sqrt{3}x+2y=-5\end{matrix}\right.\)
a) Ta có: \(\left\{{}\begin{matrix}-x+2y=3\\3x+y=-1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}-3x+6y=9\\3x+y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}7y=8\\-x+2y=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{8}{7}\\-x=3-2y=3-2\cdot\dfrac{8}{7}=\dfrac{5}{7}\end{matrix}\right.\)
hay \(\left\{{}\begin{matrix}x=-\dfrac{5}{7}\\y=\dfrac{8}{7}\end{matrix}\right.\)
Vậy: Hệ phương trình có nghiệm duy nhất là \(\left\{{}\begin{matrix}x=-\dfrac{5}{7}\\y=\dfrac{8}{7}\end{matrix}\right.\)
b) Ta có: \(\left\{{}\begin{matrix}2x+2\sqrt{3}\cdot y=1\\\sqrt{3}x+2y=-5\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2\sqrt{3}x+6y=\sqrt{3}\\2\sqrt{3}x+4y=-10\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2y=\sqrt{3}+10\\\sqrt{3}x+2y=-5\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{\sqrt{3}+10}{2}\\x\sqrt{3}+2\cdot\dfrac{\sqrt{3}+10}{2}=-5\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{\sqrt{3}+10}{2}\\x\sqrt{3}=-5-\sqrt{3}-10=-15-\sqrt{3}\end{matrix}\right.\)
hay \(\left\{{}\begin{matrix}x=-1-5\sqrt{3}\\y=\dfrac{\sqrt{3}+10}{2}\end{matrix}\right.\)
Vậy: Hệ phương trình có nghiệm duy nhất là \(\left\{{}\begin{matrix}x=-1-5\sqrt{3}\\y=\dfrac{\sqrt{3}+10}{2}\end{matrix}\right.\)
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a, \(\left\{{}\begin{matrix}\\6x+2y=-2\end{matrix}\right.-6x+12y=18}\)
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Giải hệ phương trình:1. left{{}begin{matrix}sqrt{x}+2sqrt{-1}54sqrt{x}-sqrt{y-1}2end{matrix}right.2. left{{}begin{matrix}sqrt{3x-1}-sqrt{2y+1}12sqrt{3x-1}+3sqrt{2y+1}12end{matrix}right.3. left{{}begin{matrix}sqrt{x-2}+sqrt{y-3}32sqrt{x-2}-3sqrt{y-3}-4end{matrix}right.4. left{{}begin{matrix}2sqrt{x+1}-3sqrt{-2}54sqrt{x+1}+sqrt{y-2}17end{matrix}right.
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Giải hệ phương trình:
1. \(\left\{{}\begin{matrix}\sqrt{x}+2\sqrt{-1}=5\\4\sqrt{x}-\sqrt{y-1}=2\end{matrix}\right.\)
2. \(\left\{{}\begin{matrix}\sqrt{3x-1}-\sqrt{2y+1}=1\\2\sqrt{3x-1}+3\sqrt{2y+1}=12\end{matrix}\right.\)
3. \(\left\{{}\begin{matrix}\sqrt{x-2}+\sqrt{y-3}=3\\2\sqrt{x-2}-3\sqrt{y-3}=-4\end{matrix}\right.\)
4. \(\left\{{}\begin{matrix}2\sqrt{x+1}-3\sqrt{-2}=5\\4\sqrt{x+1}+\sqrt{y-2}=17\end{matrix}\right.\)
2) Ta có: \(\left\{{}\begin{matrix}\sqrt{3x-1}-\sqrt{2y+1}=1\\2\sqrt{3x-1}+3\sqrt{2y+1}=12\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2\sqrt{3x-1}-2\sqrt{2y+1}=2\\2\sqrt{3x-1}+3\sqrt{2y+1}=12\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}-5\sqrt{2y+1}=-10\\\sqrt{3x-1}-\sqrt{2y+1}=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{2y+1}=2\\\sqrt{3x-1}-2=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2y+1=4\\3x-1=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2y=3\\3x=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{3}{2}\\x=\dfrac{10}{3}\end{matrix}\right.\)
Vậy: Hệ phương trình có nghiệm duy nhất là \(\left\{{}\begin{matrix}x=\dfrac{10}{3}\\y=\dfrac{3}{2}\end{matrix}\right.\)
3) Ta có: \(\left\{{}\begin{matrix}\sqrt{x-2}+\sqrt{y-3}=3\\2\sqrt{x-2}-3\sqrt{y-3}=-4\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2\sqrt{x-2}+2\sqrt{y-3}=6\\2\sqrt{x-2}-3\sqrt{y-3}=-4\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}5\sqrt{y-3}=10\\\sqrt{x-2}+\sqrt{y-3}=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{y-3}=2\\\sqrt{x-2}+2=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y-3=4\\x-2=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=7\\x=3\end{matrix}\right.\)
Vậy: Hệ phương trình có nghiệm duy nhất là \(\left\{{}\begin{matrix}x=3\\y=7\end{matrix}\right.\)
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Bài 1:Giải hệ phương trình bằng phương pháp cộng đại số
a.left{{}begin{matrix}sqrt{2}x+2sqrt{3}y53sqrt{2}x-sqrt{3}yfrac{9}{2}end{matrix}right.
b.left{{}begin{matrix}3sqrt{5}x-4y15-2sqrt{7}3x-2y-3end{matrix}right.
c.left{{}begin{matrix}5left(x+2yright)3y-12x+43left(x-5yright)-12end{matrix}right.
d.left{{}begin{matrix}4x^2-5left(y+1right)left(2x-3right)^23left(7x+2right)5left(2y-1right)-3xend{matrix}right.
e.left{{}begin{matrix}6left(x+yright)8+2x-3y5left(y-xright)5+3x+2yend{matrix}right.
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Bài 1:Giải hệ phương trình bằng phương pháp cộng đại số
a.\(\left\{{}\begin{matrix}\sqrt{2}x+2\sqrt{3}y=5\\3\sqrt{2}x-\sqrt{3}y=\frac{9}{2}\end{matrix}\right.\)
b.\(\left\{{}\begin{matrix}3\sqrt{5}x-4y=15-2\sqrt{7}\\3x-2y=-3\end{matrix}\right.\)
c.\(\left\{{}\begin{matrix}5\left(x+2y\right)=3y-1\\2x+4=3\left(x-5y\right)-12\end{matrix}\right.\)
d.\(\left\{{}\begin{matrix}4x^2-5\left(y+1\right)=\left(2x-3\right)^2\\3\left(7x+2\right)=5\left(2y-1\right)-3x\end{matrix}\right.\)
e.\(\left\{{}\begin{matrix}6\left(x+y\right)=8+2x-3y\\5\left(y-x\right)=5+3x+2y\end{matrix}\right.\)
Giải các hệ phương trình sau bằng phương pháp cộng đại sốa) left{{}begin{matrix}x-y13x+2y5end{matrix}right.b) left{{}begin{matrix}3x+5y102x+3y3end{matrix}right.c) left{{}begin{matrix}sqrt{5x}+y2left(1-sqrt{5}right)x-y-1end{matrix}right.d) left{{}begin{matrix}sqrt{3x}-y13x+sqrt{3y}3end{matrix}right.
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Giải các hệ phương trình sau bằng phương pháp cộng đại số
a) \(\left\{{}\begin{matrix}x-y=1\\3x+2y=5\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}3x+5y=10\\2x+3y=3\end{matrix}\right.\)
c) \(\left\{{}\begin{matrix}\sqrt{5x}+y=2\\\left(1-\sqrt{5}\right)x-y=-1\end{matrix}\right.\)
d) \(\left\{{}\begin{matrix}\sqrt{3x}-y=1\\3x+\sqrt{3y}=3\end{matrix}\right.\)
Giải hệ phương trình
left{{}begin{matrix}4left(2x-y+3right)-3left(x-2y+3right)483left(3x-4y+3right)+4left(4x-2y-9right)48end{matrix}right.
left{{}begin{matrix}6left(x+yright)8+2x-3y5left(y-xright)5+3x+2yend{matrix}right.
left{{}begin{matrix}-2left(2x+1right)+1,53left(y-2right)-6x11,5-4left(3-xright)2y-left(5-xright)end{matrix}right.
left{{}begin{matrix}dfrac{8x-5y-3}{7}+dfrac{11y-4x-7}{5}12dfrac{9x+4y-13}{5}-dfrac{3left(x-2right)}{4}15end{matrix}right.
left{{}begin{matrix}2sqrt{3}x-sqrt{5}y2...
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Giải hệ phương trình
\(\left\{{}\begin{matrix}4\left(2x-y+3\right)-3\left(x-2y+3\right)=48\\3\left(3x-4y+3\right)+4\left(4x-2y-9\right)=48\end{matrix}\right.\)
\(\left\{{}\begin{matrix}6\left(x+y\right)=8+2x-3y\\5\left(y-x\right)=5+3x+2y\end{matrix}\right.\)
\(\left\{{}\begin{matrix}-2\left(2x+1\right)+1,5=3\left(y-2\right)-6x\\11,5-4\left(3-x\right)=2y-\left(5-x\right)\end{matrix}\right.\)
\(\left\{{}\begin{matrix}\dfrac{8x-5y-3}{7}+\dfrac{11y-4x-7}{5}=12\\\dfrac{9x+4y-13}{5}-\dfrac{3\left(x-2\right)}{4}=15\end{matrix}\right.\)
\(\left\{{}\begin{matrix}2\sqrt{3}x-\sqrt{5}y=2\sqrt{6}-\sqrt{15}\\3x-y=3\sqrt{2}-\sqrt{3}\end{matrix}\right.\)
a: \(\Leftrightarrow\left\{{}\begin{matrix}8x-4y+12-3x+6y-9=48\\9x-12y+9+16x-8y-36=48\end{matrix}\right.\)
=>5x+2y=48-12+9=45 và 25x-20y=48+36-9=48+27=75
=>x=7; y=5
b: \(\Leftrightarrow\left\{{}\begin{matrix}6x+6y-2x+3y=8\\-5x+5y-3x-2y=5\end{matrix}\right.\)
=>4x+9y=8 và -8x+3y=5
=>x=-1/4; y=1
c: \(\Leftrightarrow\left\{{}\begin{matrix}-4x-2+1,5=3y-6-6x\\11,5-12+4x=2y-5+x\end{matrix}\right.\)
=>-4x-0,5=-6x+3y-6 và 4x-0,5=x+2y-5
=>2x-3y=-5,5 và 3x-2y=-4,5
=>x=-1/2; y=3/2
e: \(\Leftrightarrow\left\{{}\begin{matrix}x\cdot2\sqrt{3}-y\sqrt{5}=2\sqrt{3}\cdot\sqrt{2}-\sqrt{5}\cdot\sqrt{3}\\3x-y=3\sqrt{2}-\sqrt{3}\end{matrix}\right.\)
=>\(x=\sqrt{2};y=\sqrt{3}\)
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Giải hệ phương trình \(\left\{{}\begin{matrix}\sqrt{11}x+\sqrt{5}y=16\\3x-2y=-2\sqrt{5}+3\sqrt{11}\end{matrix}\right.\)