Respostas

2014-09-01T20:21:43-03:00
12+(3x+6).(-7)-5=70
12+(-21x-42)-5=70
12-21x-42-5=70
-21x=70-12+42+5
-21x=117-12
-21x=105
x=-105/21
x=-5

Se vc substituir o valor de x na expressão dará 70=70

12+(-15+6).(-7)-5=70
12+63-5=70
75-5=70
70=70


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