Respostas

  • Usuário do Brainly
2014-07-21T19:01:08-03:00
A)
(1,5) e (-3-7)

 \left \{ {{a+b=5} \atop {-3a+b=-7}} \right.

a=5-b
subst/

-3(5-b)+b=-7

-15+3b+b=-7

4b=8

b=2

se a=5-b
   a=5-2
a=3

y=ax+b
y=3x+2

b)
 \left \{ {{-a+b=7} \atop {2a+b=1}} \right.

b=7+a

subst/
2a+b=1

2a+7+a=1

3a=-6

a=-2

se  b=7+a
     b=7-2
    b=5

y=ax+b

y=-2x+5
 
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