Here is a conundrum I pondered upon while solving an equation - 2x2 , generally means we are adding 2 two times , that is , 2+2 Then , (-2)x(-2) , should go like this (-2)+(-2)=-4 , But , that's not true , the answer is +4 . Can anybody figure out and help me with it..
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just consider $-(2 \cdot 2)$ as the opposite of $2 \cdot 2$ – Vasili Nov 16 '18 at 15:12
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$(-2) \times (-2)= 2 \times [(-1) \times (-2)]$ i.e. you are multiplying for $2$ (i.e. adding with itself) the result of "swapping the sign", i.e. mult for $(-1)$. – Mauro ALLEGRANZA Nov 16 '18 at 15:15
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We need to refer to axioms and since $+1$ is the neutral element for product, the idea is that we have
- $(-2) \cdot (+1)=-2$
and then
- $(-2) \cdot (-1)=+2 \implies (-2) \cdot (-2)=+4$
For a detailed discussion refer to the related
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