x=1+√2,y=1-√2
x+y=2 x-y=2√2
[(1/(x-y)+1/(x+y)]-【2y/(x的平方-2xy+y的平方)】
=[(x+y+x-y/(x-y)(x+y)]-【2y/(x-y)^2】
=[2(1+√2)/2*2√2]-【2(1-√2)/(2√2)^2】
=[(1+√2)/2√2]-【2(1-√2)/8】
=[(2+√2)/4]-【(1-√2)/4】
=(1+2√2)/4难道不需要化到最简再带入么x=1+√2,y=1-√2x+y=2x-y=2√2[(1/(x-y)+1/(x+y)]-【2y/(x的平方-2xy+y的平方)】 =[(x+y+x-y/(x-y)(x+y)]-【2y/(x-y)^2】=[(2x/(x-y)(x+y)]-【2y/(x-y)^2】=(2x(x-y)-2y(x+y))/(x+y)(x-y)^2=(2x^2-2xy-2xy-2y^2)/(x+y)(x-y)^2=2(x^2-2xy-y^2)/(x+y)(x-y)^2应该化成最简,当时看化简意义不大,才直接代入x、y的值
先化简再求值 [(1/(x-y)+1/(x+y)]-【2y/(x的平方-2xy+y的平方)】 其中x=1+√2,y=1-√2
先化简再求值 [(1/(x-y)+1/(x+y)]-【2y/(x的平方-2xy+y的平方)】 其中x=1+√2,y=1-√2
数学人气:793 ℃时间:2019-08-20 08:48:03
优质解答
我来回答
类似推荐
猜你喜欢
- 1已知关于x的方程a(x-3)+b(3x+1)=5(x+1)有无穷多个解,则a+b=_.
- 2n碱基对数,4^nDNA种类?为什么不是4^2n种DNA
- 3Just because some one doesn't love you the way you want them to,doesn't mean they don't love you wi
- 4已知奇函数f(x)是定义域(-3,3)上的减函数,且满足不等式f(x-3)+f(x²-3)<0,求不等式解集
- 5设函数f(x)=【根号(x2+1)】-ax,当a>=1时,试证函数f(x)在区间【0,+无穷】上是单调函数
- 6小学语文第三册功夫用到了,自然会成功时什么词语
- 7将定值电阻R1和R2并连在电压不变的电源上,R1的功率为20W,R2的功率为30W,若将它们串联后接在该电源上,求P
- 8已知一列数是:1,-3,5,-7,9,.按规律,第10个数是几?第100个数呢?第N个数呢?
- 9设fx=1/2*ax^2-2ax+lnx ,已知函数fx有两个极值点x1x2
- 10已知函数f(x)=√3sin(wx+φ)-cos(wx+φ)(0