想請教填充7和問答2 謝謝
填充7.
\(x,y,z\)為正實數,\(\Bigg\{ \matrix{x^2+xy+y^2=9 \cr y^2+yz+z^2=16 \cr z^2+zx+x^2=25}\),求\(x+y+z=\)?
105.5.6補充
若三正實數\(x,y,z\)滿足\(\Bigg\{ \matrix{x^2+xy+y^2=25 \cr y^2+yz+z^2=49 \cr z^2+zx+x^2=64}\),則\(x+y+z\)之值為何?
(建中通訊解題 第97期,
http://web2.ck.tp.edu.tw/~mathwe ... 30-15&Itemid=37)