作业帮初二英语句型转换和有关分式的数学问题.急.英语：It's about twenty minuture on foot from here to the bank.(同义句转换）It's about _ _ _ from here to the bank .①.已知分式x+2y/ 2-xy的值为a,如果把x,y换成它们的
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/02 11:00:54
初二英语句型转换和有关分式的数学问题.急.英语：It's about twenty minuture on foot from here to the bank.(同义句转换）It's about _ _ _ from here to the bank .①.已知分式x+2y/ 2-xy的值为a,如果把x,y换成它们的
初二英语句型转换和有关分式的数学问题.急.
英语：It's about twenty minuture on foot from here to the bank.(同义句转换）
It's about _ _ _ from here to the bank .
①.已知分式x+2y/ 2-xy的值为a,如果把x,y换成它们的相反数,所得的值是b,请判断a与b之间的关系,并说明理由.
②.已知x²-3x+1=0,求x²+1/x²的值.
③.已知x+1/x=3,求x²/x^4+x²+1的值.
④.化简x²-2x/2y-xy
初二英语句型转换和有关分式的数学问题.急.英语：It's about twenty minuture on foot from here to the bank.(同义句转换）It's about _ _ _ from here to the bank .①.已知分式x+2y/ 2-xy的值为a,如果把x,y换成它们的
英语：twenty minutes' walk
数学：
1.（x+2y)/(2-xy)=a x+2y=a*(2-xy)
把x y换成相反数,则有公式(-x-2y)/(2-xy)=b x+2y=b*[-(2-xy)]
综上：a*(2-xy) =b*[-(2-xy)]
所以：a=-b 即a b互为相反数.
2.因为x²-3x+1=0.此式左右两边均除以x 得：x+1/x=3
因为x²+1/x²=(x+1/x)²-2 所以：x²+1/x²＝7
4.（x²-2x)/(2y-xy)=x(x-2)/y(2-x) = -x/y
不好意思,我想了半天,第三个我也不会做^-^
英语:It's about twenty minutes' walk.....
英语。。takes him twenty minutes to walk
数学。。做不出来
twenty minutes'wallking