Question

{4х+3у=5
{3х+5у=1
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Answer 1

Ответ:  ( 2  ; -1  )

Объяснение:

$\left \{\begin{array}{l}4x+3y = 5 ~~ \big |\cdot 3 \\\\ 3x+5y = 1 ~~ \big |\cdot 4\end{array} \right. \Leftrightarrow \ominus \left \{\begin{array}{l}12x+9y = 15 \\\\ 12x+20y = 4\end{array} \Leftrightarrow$


$12x-12x+9y -20y = 15-4 \\\\ -11y = 11 \\\\ y =-1 \\\\ x=\dfrac{1-5y}{3} = 2$

Answer 2

Ответ:  $x=2;y=-1$

Пошаговое решение:

$\displaystyle \left \{ {4x+3y=5} \atop {3x+5y=1}} \right. \Leftrightarrow\left \{ {{4x+3y=5|:4} \atop {3x+5y=1}} \right. \Leftrightarrow \left \{ {{x=1,25-0,75y} \atop {3x+5y=1}} \right.$

$3x+5y=1\\3*(1,25-0,75y)+5y=1\\3,75-2,25y+5y=1\\3,75+2,75y=1\\2,75y=1-3,75\\2,75y=-2,75|:2,75\\y=-1$

$4x+3y=5\\4x+3*-1=5\\4x-3=5\\4x=5+3\\4x=8|:4\\x=2$