a, \(\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)

b,\(\left\{{}\begin{matrix}x=3\\y=4\end{matrix}\right.\)

c,\(\left\{{}\begin{matrix}x=1\\y=1\end{matrix}\right.\)

d,\(\left\{{}\begin{matrix}x=0\\y=2\end{matrix}\right.\)

\(a.\left\{{}\begin{matrix}3x+y=-2\\-9x-39=6\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}y=-2-3x\\-9x-36=6\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}y=-2-3x\\-9x=45\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}y=-2-3x\\x=-5\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-5\\y=13\end{matrix}\right.\)

\(b.\left\{{}\begin{matrix}x+y=101\\-x+y=-1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=101-y\\-x+y=-1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=101-y\\-101+y+y=-1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=101-y\\2y=100\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=101-y\\y=50\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=51\\y=50\end{matrix}\right.\)

\(c.\left\{{}\begin{matrix}x+y=2\\\dfrac{1}{2}x+y=\dfrac{5}{4}\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2-y\\\dfrac{1}{2}x+y=\dfrac{5}{4}\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2-y\\1-\dfrac{1}{2}y+y=\dfrac{5}{4}\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2-y\\\dfrac{1}{2}y=\dfrac{1}{4}\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=2-y\\y=\dfrac{1}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{2}\\y=\dfrac{1}{2}\end{matrix}\right.\)

deo bit lam

\(\Leftrightarrow\left\{{}\begin{matrix}-2x+5y=-5\\2x+3y=5\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}8y=0\\2x+3y=5\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{5}{2}\\y=0\end{matrix}\right.\)

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)\(\left\{{}\begin{matrix}9x=-18\\4x+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\4.\left(-2\right)+3y=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=7\end{matrix}\right.\)

bạn giải câu g hộ mỉnh đc ko

1) \(\Leftrightarrow\left\{{}\begin{matrix}a=2+b\\b\left(2+b\right)-\left(2+b\right)-34=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}a=2+b\\b^2+b-36=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}a=2+b\\b=\frac{-1\pm\sqrt{145}}{2}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=2+\frac{-1\pm\sqrt{145}}{2}\\b=\frac{-1\pm\sqrt{145}}{2}\end{matrix}\right.\)