Question

Resolver las siguientes ecuaciones lineales de dos incógnitas por el método de sustitución


$\left \{ {{4+x=2y} \atop {2x-y=1}} \righ$


$\left \{ {{2x+y=7} \atop {x+3y=11}} \right.$


$\left \{ {{-10x-5y=0} \atop {21x-7y=28}} \right.$



ayudaa doy estrellas

Answer 1

Respuesta:

1. x=2, y=3

2. x=2, y=3

3. x= - 4, y= - 8

Explicación paso a paso:

1.

$4+x=2y=x=2y-4\\2x-y=1=2-y=1\\2(\frac{2y-4}{1})-y=1\\4y-8-y=1\\4y-y=1+8\\3y=9\\y=\frac{9}{3}=3\\\\4+x=2(3)\\4+x=6\\x=6-4\\x=2$

2.

$2x+y=7=2x=7-y\\x+3y=11=1+3y=11\\1(\frac{7-y}{2})+3y=11\\\frac{7-y+6y}{2}=11\\\frac{6y-y}{2}=\frac{22-7}{2}\\\frac{5y}{2}=\frac{15}{2}\\y=\frac{15}{5}=y=3\\\\2x+1(3)=7\\2x+3=7\\2x=7-3\\2x=4\\x=\frac{4}{2}=x=2$

3.

$-10x-5y=0=-10x=5y\\21x-7y=28=21-7y=28\\21(\frac{5y}{-10})-7y=28\\-\frac{105y+70y}{10}=28\\-\frac{35y}{10}=\frac{280}{10}\\y=-\frac{280}{35}=y=-8\\\\-10x-5(-8)=0\\-10x+40=0\\-10x=40\\x=-\frac{40}{10}=x=-4$

Espero te ayude mucho, corona por favor.