Răspuns :
Răspuns:
Explicație:
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<p style="text-align:center"> (a + b)<sup>2</sup>=a<sup>2</sup>+2ab+b<sup>2</sup>
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<p style="text-align:center"> (a<sub>1</sub>+a<sub>2</sub>+a<sub>3</sub>)=a<sub>1</sub><sup>2</sup> + a<sub>2</sub><sup>2</sup>+a<sub>3</sub><sup>2</sup>+2a<sub>1</sub>a<sub>2</sub>+2a<sub>1</sub>a<sub>3</sub>+2a<sub>2</sub>a<sub>3</sub>
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<p style="text-align:center"> abs(a+b) < abs(a)+ abs(b)
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