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Calculati: (2x-y)²;(4+2x)²; (2√2-3a)(2√2+3a);

Răspuns :

[tex](2x-y)^2 = 4x^2 - 2*2x*y +y^2= 4x^2 - 4xy+ y^2[/tex]
[tex](4+2x)^2 = 16+2*2x*4+4x^2 = 16+16x+4x^2[/tex]
[tex](2 \sqrt{2} -3a)(2 \sqrt{2} +3a) = 4*2 - 9a^2 = 8-9a^2[/tex]
Formulele de calcul prescurtat
[tex](2x-y)^2=(2x)^2-2 \cdot 2x \cdot y+y^2=4x^2-4xy+y^2 \\ (4+2x)^2=4^2+2 \cdot 4 \cdot 2x+(2x)^2=16+16x+4x^2 \\ (2 \sqrt{2} -3a)(2 \sqrt{2} +3a)=8-9a^2[/tex]