Question

giải phương trình sau 5x - 4y = 32 

                                    2x + 3y = -1

Answer 1

\(\left\{{}\begin{matrix}5x-4y=32\\2x+3y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}10x-8y=64\\10x+15y=-5\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}-23y=69\\2x+3y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}y=-3\\2x+3.\left(-3\right)=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}y=-3\\2x-9=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}y=-3\\2x=8\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}y=-3\\x=4\end{matrix}\right.\)

Vậy hpt có nghiệm là \(\left(x;y\right)=\left(4;-3\right)\)

Answer 2

\(\left\{{}\begin{matrix}5x-4y=32\\2x+3y=-1\end{matrix}\right.\)

⇔\(\left\{{}\begin{matrix}5x-4y=32\\5x+7,5y=-\dfrac{5}{2}\end{matrix}\right.\)

⇔\(\left\{{}\begin{matrix}5x-4y=32\\-\dfrac{23}{2}y=\dfrac{69}{2}\end{matrix}\right.\)

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

Vậy HPT có nghiệm (x;y) = (4;-3)

 

Answer 3

\(\left\{{}\begin{matrix}5x-4y=32\\2x+3y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}10x-8y=64\\10x+15y=-5\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x+3y=-1\\-23y=69\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}2x+3.\left(-3\right)=-1\\y=-3\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=4\\y=-3\end{matrix}\right.\)

 

Answer 4

{5x−4y=322x+3y=−1⇔{10x−8y=6410x+15y=−5⇔{−23y=692x+3y=−1⇔{y=−32x+3.(−3)=−1⇔{y=−32x−9=−1⇔{y=−32x=8⇔{y

Answer 5

\(\begin{cases} 5x-4y=32\\ 2x+3y=-1 \end{cases} \)

➞\(\begin{cases} 10x-8y=64\\ 10x+15y=-5 \end{cases} \)

➜\(\begin{cases} -23y=69\\ 10x+15y=-5 \end{cases} \)

➜\(\begin{cases} x=-3\\ y=4 \end{cases} \)

`vậy hpt có nghiệm duy nhất (x;y)=(-3;4)`