Resposta:
[tex](3x - 2) + (x - 4) - (2x - 1)\\\\3x-2+x-4-\left(2x-1\right)\\\\-\left(2x-1\right)=-2x+1\\\\3x-2+x-4-2x+1\\\\2x-5[/tex]
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[tex](a-2 a + ab - b)-(a + 2ab - b)\\\\a-2a+ab-b-\left(a+2ab-b\right)\\\\-\left(a+2ab-b\right)=-a-2ab+b\\\\a-2a+ab-b-a-2ab+b\\\\-ab-2a[/tex]
