Question

化简求值a+1分之1-a^2-2a+1分之a+1除以a-1分之a+1,其中a=根号2

1计算x^2+xy+y^2，2：x^2-y^2

Answer 1

解
1/(a+1)-(a+1)/(a²-2a+1)÷(a+1)/(a-1)
=1/(a+1)-(a+1)/(a-1)²×(a-1)/(a+1)
=1/(a+1)-1/(a-1)
=(a-1)/(a+1)(a-1)-(a+1)/(a-1)(a+1)
=(a-1-a-1)/(a²-1)
=(-2)/[(√2)²-1]
=-2/(2-1)
=-2

追问

1计算x^2+xy+y^2，2：x^2-y^2

追答

是分解因式还是什么

追问

计算，每答一题我会加5分的

追答

计算什么，没x和y的值，不能计算

追问

哦，看掉题目了= =
已知x=根号3+1，y=根号3-1

追答

呵呵
x=√3+1，y=√3-1
x+y=√3+1+√3-1=2√3
xy=(√3+1)(√3-1)=3-1=2
∴x²+xy+y²
=(x+y)²-xy
=(2√3)²-2
=12-2
=10

x²-y²
=(x-y)(x+y)
=2√3(√3+1-√3+1)
=2√3×2
=4√3

Answer 2

给个图吧，乱

Answer 3

这么乱啊