设函数y=f(x)由方程2y^3-2y^2+2xy-x^2=1所确定的,求解f(x)的极值

2024-11-05 22:46:14
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两边对x求导:
6y^2*y'-4y*y'+2y+2xy'-2x=0
即y'=(x-y)/(3y^2-2y+x)
令y'=0, 得:x=y
再将x=y代入原方程,得:2x^3-2x^2+2x^2-x^2=1, 得:2x^3-x^2-1=0
2x^3-2x^2+x^2-1=0
2x^2(x-1)+(x-1)(x+1)=0
(x-1)(2x^2+x+1)=0
得唯一根x=1,
即极值点为(1, 1), 极值即为y=f(1)=1.