分母有理化
x=(√3-√2)²/(√3-√2)(√3+√2)
=(3-2√6+2)/(3-2)
=5-2√6
同理y=5+2√6
x-y=-4√6
xy=25-24=1
原式=3x²-6xy+3y²+xy
=3(x-y)²+xy
=3×(-4√6)²+1
=289
因为x=(根号3-根号2)/(根号3+根号2)=5-2√6,
y=(根号3+根号2)/(根号3-根号2)=5+2√6
所以
x^2+y^2=(5-2√6)^2+(5+2√6)^2=50+48=98
xy=1
从而:
3x^2-5xy+3y^2=3*(x^2+y^2)-5xy=3*98-5=289.