Respostas

2014-07-22T19:10:42-03:00
X+y = 8
x-y=4

x = 4 + y

substituindo:
x+y =8
(4+y)+y =8
4+ 2y = 8
2y= 4
y= 2

x = 4 + y
x = 4 + 2
x= 6

x² - y²= 6² - 2² = 36 - 4 = 32

x²-y² = 32


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