y=x^(3/2)+(1-x)^(3/2)
y'=(3/2)x^(1/2)-(3/2)(1-x)^(1/2)
y'=0
x^(1/2)-(1-x)^(1/2)=0
x=(1-x)
x=1/2
x<(1/2),y'<0
x>(1/2),y'>0
x=1/2,y最小值=2√(1/2)^3=1/(√2)