Question

POR FAVOR, ME AJUDEM

Resolva os sistemas aplicando qualquer método de resolução:

Answer 1

a) a) $\left \{ {{x+y=9} \atop {x-y=5}} \right.$

 $\left \{ {{x=9} \atop {x=5}} \right.$

 x=14   14+y=9

 y=9-14

 y=-5

b) $\left \{ {{4x-y=8} \atop {x+y=7}} \right.$

 $\left \{ {{4x=8} \atop {x=7}} \right.$

 5x=15 x=$\frac{15}{5}$ x=3 3+y=7 y=7-3 y=4

c) $\left \{ {{x=6y} \atop {2x-7y=10}} \right.$  

$\left \{ {{x=6y .(-2)} \atop {2x-7y=10}} \right.$

 $\left \{ {{-2x=-12y} \atop {2x-7y=10}} \right.$  

$\left \{ {{-12y} \atop {-7y=10}} \right.$

 -19y=10 y=$\frac{10}{-19}$  

x=6.$(\frac{10}{-19})$ x=$\frac{60}{-19}$

d) $\left \{ {{x-3y=5} \atop {2x+4y=0}} \right.$  

$\left \{ {{x-3y=5.(-2)} \atop {2x+4y=0}} \right.$  

$\left \{ {{-2x+6y=-10} \atop {2x+4y=0}} \right.$  

$\left \{ {{6y=-10} \atop {4y=0}} \right.$

 10y=-10 y=-1 x-3.(-1)=5 x+3=5 x=5-3 x=2

e) $\left \{ {{2x+3y=2} \atop {4x-9y=-1}} \right.$  

$\left \{ {{2x+3y=2.(3)} \atop {4x-9y=-1}} \right.$  

$\left \{ {{6x+9y=6} \atop {4x-9y=-1}} \right.$  

$\left \{ {{6x=6} \atop {4x=-1}} \right.$  

10x=5 x=$\frac{5}{10}$

 x=0,5 2.0,5+3y=2 1+3y=2 3y=2-1 y=$\frac{1}{3}$

f) $\left \{ {{3x+2y=5} \atop {4x+y=5}} \right.$  

$\left \{ {{3x+2y=5} \atop {4x+y=5.(-2)}} \right.$  

$\left \{ {{3x+2y=5} \atop {-8x-2y=-10}} \right.$  

$\left \{ {{3x=5} \atop {-8x=-10}} \right.$ -5x=-5 x=1 3.1+2y=5  

3+2y=5 2y=5-3 y=$\frac{2}{2}$  

y=1

g) $\left \{ {{x-y=5} \atop {x+9y=9}} \right.$  

$\left \{ {{x-y=5.(-1)} \atop {x+9y=9}} \right.$  

$\left \{ {{-x+y=-5} \atop {x+9y=9}} \right.$  

$\left \{ {{y=-5} \atop {9y=9}} \right.$  

10y=4 y=$\frac{4}{10}$ x-$\frac{4}{10}$=5  x=5+$\frac{4}{10}$   x=$\frac{54}{10}$ /2 x=$\frac{27}{5}$

h) $\left \{ {{3x-2y=6} \atop {x-3y=2}} \right.$  

$\left \{ {{3x-2y=6} \atop {x-3y=2.(-3)}} \right.$  

$\left \{ {{3x-2y=6} \atop {-3x+9y=-6}} \right.$ $\left \{ {{-2y=6} \atop {9y=-6}} \right.$

 7y=0 y=0 x-3.0=2 x=2

i) $\left \{ {{x+y=4} \atop {2x+y=7}} \right.$  

$\left \{ {{x+y=4.(-1)} \atop {2x+y=7}} \right.$  

$\left \{ {{-x-y=-4} \atop {2x+y=7}} \right.$  

$\left \{ {{-x=-4} \atop {2x=7}} \right.$ x=3 3+y=4 y=1

j) $\left \{ {{x-y=1} \atop {x-3y=3}} \right.$  

$\left \{ {{x-y=1.(-1)} \atop {x-3y=3}} \right.$  

$\left \{ {{-x+y=-1} \atop {x-3y=3}} \right.$  

$\left \{ {{y=-1} \atop {-3y=3}} \right.$

 2y=2 y=1 x-1=1 x=0

k) $\left \{ {{2x+5y=16.(2)} \atop {3x+2y=2(.-5)}} \right.$  

$\left \{ {{4x+10y=32} \atop {-15x-10y=-10}} \right.$  

$\left \{ {{4x=32} \atop {-15x=-10}} \right.$ 11x=22 x=2 2.2+5y=16 4+5y=16 5y=16-4 5y=12 y=$\frac{12}{5}$