[tex]\text{If is}\\\\\left\{\begin{array}{ccc}0.2-0.3y=4\\2.3x-y=1.2\end{array}[/tex]
Answer:
[tex]\large\boxed{\left(-\dfrac{344}{69},\ -\dfrac{38}{3}\right)}[/tex]
Step-by-step explanation:
[tex]\left\{\begin{array}{ccc}0.2-0.3y=4\\2.3x-y=1.2&\text{multiply both sides by (-0.3)}\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}0.2-0.3y=4\\-0.69x+0.3y=-0.36\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad-0.69x+0.2=3.64\qquad\text{subtract 0.2 from both sides}\\.\qquad-0.69x=3.44\qquad\text{divide both sides by (-0.69)}\\.\qquad x=-\dfrac{3.44\cdot100}{0.69\cdot100}\\.\qquad \boxed{x=-\dfrac{344}{69}}\\\\\text{Calculate the value of y from first equation:}[/tex]
[tex]0.2-0.3y=4\qquad\text{subtract 0.2 from both sides}\\-0.3y=3.8\qquad\text{divide both sides by (-0.3)}\\y=-\dfrac{3.8\cdot10}{0.3\cdot10}\\\boxed{y=-\dfrac{38}{3}}[/tex]
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[tex]\text{If is}\\\\\left\{\begin{array}{ccc}0,2x-0,3y=4\\2.3x-y=1.2\end{array}\right[/tex]
Answer:
[tex]\large\boxed{\left(-\dfrac{52}{7},\ -\dfrac{128}{7}\right)}[/tex]
Step-by-step explanation:
[tex]\left\{\begin{array}{ccc}0.2x-0.3y=4&\text{multiply both sides by 10}\\2.3x-y=1.2&\text{multiply both sides by 10}\end{array}\right\\\\\left\{\begin{array}{ccc}2x-3y=40&\text{multiply both sides by (-10)}\\23x-10y=12&\text{multiply both sides by 3}\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}-20x+30y=-400\\69x-30y=36\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad49x=-364\qquad\text{divide both sides by 49}\\x=-\dfrac{364:7}{49:7}\\.\qquad\boxed{x=-\dfrac{52}{7}}[/tex]
[tex]2\left(-\dfrac{52}{7}\right)-3y=40\\-\dfrac{104}{7}-3y=40\qquad\text{multiply both sides by 7}\\-104-21y=280\qquad\text{add 104 to both sides}\\-21y=384\qquad\text{divide both sides by (-21)}\\y=-\dfrac{384:3}{21:3}\\\boxed{y=-\dfrac{128}{7}}[/tex]
