具体放在补充里,捉急!
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/09/02 04:17:12
具体放在补充里,捉急!
![](http://img.wesiedu.com/upload/6/25/625d5e32b594d61fadbec9ba75a87849.jpg)
![](http://img.wesiedu.com/upload/6/25/625d5e32b594d61fadbec9ba75a87849.jpg)
8x^2-26xy+15y^2=(4x-3y)(2x-5y)
ab(c^2-d^2)+cd(a^2-b^2)=abc^2-abd^2+a^2cd-b^2cd
=ac(bc+ad)-bd(ad+bc)
=(ac-bd)(bc+ad)
∵x=(√3-√2)/(√3+√2)
=5-2√6
x^2=(5-2√6)/(5+2√6)
∴1/x^2=(5+2√6)/(5-2√6)
=49+20√6
又y=(√3+√2)/(√3-√2)
=5+2√6
y^2=(5+2√6)/(5-2√6)
1/y^2=(49-20√6)
∴(y/x^2)+(x/y^2)=(5+2√6)(49+20√6)+(5-2√6)(49-20√6)
=970
ab(c^2-d^2)+cd(a^2-b^2)=abc^2-abd^2+a^2cd-b^2cd
=ac(bc+ad)-bd(ad+bc)
=(ac-bd)(bc+ad)
∵x=(√3-√2)/(√3+√2)
=5-2√6
x^2=(5-2√6)/(5+2√6)
∴1/x^2=(5+2√6)/(5-2√6)
=49+20√6
又y=(√3+√2)/(√3-√2)
=5+2√6
y^2=(5+2√6)/(5-2√6)
1/y^2=(49-20√6)
∴(y/x^2)+(x/y^2)=(5+2√6)(49+20√6)+(5-2√6)(49-20√6)
=970