Question

no sistema x+y=400 x-y=200.O valor de 4x-2y é:!:

Answer 1

■ x + y = 400
■ x - y = 200

2x = 600
x = 600/2
x = 300

x - y = 200
300 - y = 200
-y = 200 - 300
-y = -100
y = 100

S={(300,100)}

4x - 2y = 4*300 - 2*100 = 1200 - 200 = 1000


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06/10/2016
Sepauto 
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Answer 2

x+y=400 => x = 400 - y
x-y=200

Substituindo na eq 2:

400 - y - y = 200
-2y = -200
y = 100

Em: x = 400 - y
x = 300

Logo:

4x-2y:
4*300-2*100 = 1000