Question

(a+b-c).(a-b-c), quando a=2, b=-3 e c=-1. Explique​

Answer 1

Basta trocar letra pelo respectivo número.

$(a+b-c).(a-b-c)$

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$\left(2+\left(-3\right)-\left(-1\right)\right)\left(2-\left(-3\right)-\left(-1\right)\right)\\\\=0\cdot \left(2-\left(-3\right)-\left(-1\right)\right)\\\\=0\cdot \:6\\\\=0$