Question

Resolva os seguintes sistemas de equações com duas variáveis:
obs: VALENDO 15 PONTOS, É URGENTE! DESDE JÁ AGRADEÇO.
x+y=40
x-y=26
?

2x-y=5
x+y=4
?

x+y=1
x-y=1
?

x+y=13
x-2y=4
?

Answer 1

Questão 01

$\left \{ {{x+y=40} \atop {x-y=26}} \right.$
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$y=40-x$
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$x-y=6$
$x-(40-x)=26$
$x-40+x=26$
$2x=26+40$
$2x=66$
$x= \frac{66}{2}$
$x=33$
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$y=4-x$
$y=4-(33)$
$y=4-33$
$y=-29$
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$s=(33,-29)$
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Questão 02

$\left \{ {{2x-y=5} \atop {x+y=4}} \right.$
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$2x=5+y$
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$x+y=4$
$5+y+y=4$
$2y=4+5$
$y= \frac{9}{2}$
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$2x=5+y$
$2x=5+ \frac{9}{2}$
$2x= \frac{10}{2} + \frac{9}{2}$
$2x=10+9$
$2x=19$
$x= \frac{19}{2}$
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$s=( \frac{19}{2}, \frac{9}{2} )$
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Questão 03

$\left \{ {{x+y=1} \atop {x-y=1}} \right.$
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$x=1+y$
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$x+y=1$
$1+y+y=1$
$2y=1-1$
$y= \frac{0}{2}$
$y=0$
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$x=1+y$
$x-0=1$
$x=1$
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$s=(1,0)$
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Questão 04

$\left \{ {x+y=13} \atop {x-2y=4}} \right.$
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$y=13-x$
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$x-2y=4$
$x-2(13-x)=4$
$x-26+2x=4$
$3x=4+26$
$3x=30$
$x= \frac{30}{3}$
$x=10$
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$y=13-x$
$y=13-10$
$y=3$
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$s=(10,3)$
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Espero ter ajudado!