已知x+y=5,x-y=3,求:x^2-y^2 x^2+y^2 xy的结果
已知x+y=5,x-y=3,求:x^2-y^2 x^2+y^2 xy的结果
其他人气:189 ℃时间:2020-02-01 09:33:26
优质解答
x^2-y^2 =(x+y)(x-y) =5*3 =15 x^2+y^2 =1/2(x+2xy+y+x-2xy+y)] =1/2[(x+y)+(x-y)] =1/2(25+9) =17 xy =1/4[(x+2xy+y)-(x-2xy+y)] =1/4[(x+y)-(x-y)] =1/4(25-9) =4
我来回答
类似推荐
猜你喜欢
- 1there was ()rain last year,so the plants didn't grow well是选择题其中little 与much我都想选
- 2英语作文 my hope in the future
- 3为什么这段话要有个分号呢:遇到困难,他总是想:这是中国人自己修筑的第一条铁路,一定要把它修好;否则
- 49/8x=6/1*21/16
- 5英语翻译
- 6猜字谜:上面是日;下面是火;左边是言;右边是见,求中间一个字,中间那个字和上下左右的字都能组成.
- 7美丽的上海外滩夜景应该用什么词形容
- 8Doplphins can walk on water and play with balls.They are smart and( ).
- 9be+形容词+介词 的短语!
- 10开心学英语六年级下册所有单词