Question

Equação por substituição!

2x+3y=8
7x-2y=3

Answer 1

Resposta:

$\left \{ {{I)2x+3y=8} \atop {II)7x-2y=3}} \right.$

${{I)2x+3y=8} =>2x =8-3y = > x=\frac{8-3y}{2}$

Substituindo I em II temos

7x-2y = 3

$7.(\frac{8-3y}{2})-2y = 3$

$(\frac{56-21y}{2})-2y = 3$

$(\frac{56-21y}{2})-\frac{2}{2} 2y = 3$

$(\frac{56-21y}{2})-\frac{4}{2} y = 3$

$\frac{56-21y-4y}{2} = 3$

$56-21y-4y = 3.2$

$-25y = 6 - 56$

$-25y =- 50$

$y =\frac{-50}{-25}$

$=> y=2$

$I) x=\frac{8-3y}{2}$

$x=\frac{8-3.2}{2}$

$x=\frac{8-6}{2}$

$x=\frac{2}{2}$

$=>x=1$