Question

已知x=根号3减根号2分之根号3加根号2,y=根号3加根号2分之根号3减根号2式子3x的平方减5xy加3y的平方的值为

Answer 1

因x=(√3+√2)/(√3-√2)=5+2√6

y=(√3-√2)/(√3+√2)=5-2√6

所以x-y=4√6,xy=1

所以3x^2-5xy+3y^2=3x^2-6xy+3y^2+xy

=3(x-y)^2+xy

=3×（4√6）^2+1

=289