来源:学生作业帮 编辑:搜狗做题网作业帮 分类:数学作业 时间:2024/06/30 19:54:38
求正确答案,还要有式子!
![](http://img.wesiedu.com/upload/a/0a/a0a7560f950fe892fe8fdfc588101432.jpg)
x^2+xy+y^2
=x^2+2xy+y^2-xy
=(x+y)^2-xy x=√2+1 y=√2-1 x+y=2√2 xy=1
=(2√2)^2-1
=8-7
=7
3(a+1)^2-(a+1)(2a-1)
=3(a^2+2a+1)-(2a^2+a-1)
=3a^2+6a+3-2a^2-a+1
=a^2+5a+4
=(a+1)(a+4) a=1
=2*5
=10
再问: 谢谢啦!