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2014-08-04T14:29:28-03:00
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2014-08-04T14:40:44-03:00
P1= a+b+c

p2=a-b+c

p3=a+b-c

calcule
a)
p1+p2+p3=

a+b+c+a-b+c+a+b-c=
a+a+a+b-b+b+c+c-c=
3a+2b+2c

b)
p1+p2-p3=

a+b+c+a-b+c-(a+b-c)=
a+b+c+a-b+c-a-b+c=
a+a-a+b-b-b+c+c+c=
2a-2b+3c

c)
p1-p2+p3

a+b+c-(a-b+c)+a+b-c=
a+b+c-a-b-c+a+b-c=
a-a+a+b-b+b+c-c-c=
2a+3b-2c

d)
p1-p2-p3=

a+b+c-(a-b+c)-(a+b-c)=
a+b+c-a+b-c-a-b+c=
a-a-a+b+b-b+c-c+c=
-2a+2b+2c
2 5 2