Question

a) Arătați că :
$x ^{2} + y ^{2} + 4x - 6y + 13 = (x + 2) ^{2} + (y - 3) ^{2}$
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Answer 1

$x^{2} +y^{2} +4x-6y+13=(x+2)^{2} + (y-3)^{2} \\x^{2} +y^{2} +4x-6y+13=x^{2} +4x+4+y^{2} -6y+9\\x^{2} +y^{2} +4x-6y+13=x^{2} +y^{2} +4x-6y+13$

• Afirmatie adevarata!