[考古] 86交大

[topractise (連月亮都幫我!)]

Find all maxima and the minima of the function f(x,y) = xy + x^3 on the

              2       2
             x       y
region S   ----- + -----    <  1
             4       2      =

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→ ht15trep:fx=0和fy=0得到的(0,0)D<0為鞍點
→ ht15trep:x=2cosΘ,y=(√2)sinΘ代入原式求極值
→ topractise:我要的是真的算的出來的解法