อ้างอิง:
ข้อความเดิมเขียนโดยคุณ <KAB555>
$(1+\sqrt{2} +\sqrt{3} )(1+\sqrt{2} -\sqrt{3} )(1-\sqrt{2} +\sqrt{3} )(1-\sqrt{2} -\sqrt{3})$ เท่ากับเท่าไหร่
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$(1+\sqrt{2} +\sqrt{3} )(1+\sqrt{2} -\sqrt{3} )(1-\sqrt{2} +\sqrt{3} )(1-\sqrt{2} -\sqrt{3})$
$= ((1+\sqrt{2})^3-(\sqrt{3})^2)((1-\sqrt{2})^2-(\sqrt{3})^2)$
$= (3+2\sqrt{2}-3)(3-2\sqrt{2}-3) $
$= (2\sqrt{2})(-2\sqrt{2}) $
$= -8$