Question

resolva os sistemas abaixo
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Answer 1

Resposta:

a)-

$\left \{ {{2x+y=7} \atop {x-y=8}} \right. \\\left \{ {{y=7-2x} \atop {x-y=8}} \right. \\x-(7-2x)=8\\x=5\\y=7-2*5\\y=-3$

b)-

$\left \{ {{x-y=5} \atop {3(x+y)=27}} \right. \\\left \{ {{x=5+y} \atop {3x+y)=27}} \right. \\3(5+y+y)=27\\y=2\\x=5=2=7$

c)-

$\left \{ {{2x-y=7} \atop {x+5y=-2}} \right. \\\left \{ {{y=-7=2x} \atop {x+5y=-2}} \right. \\x+5(-7=2x)=-2\\x=3\\y=-7+2*3=-1$

d)-

$\left \{ {{3a=16+b} \atop {2(a+1)-3(b+2)=a}} \right. \\\left \{ {{b-16+3a} \atop {2(a+1)-3(b+2)=a}} \right. \\2(a+1) - 3(-16 +3a+2) = a\\a=\frac{11}{2} \\b= \frac{1}{2}$