(x+y)^2=49
x^2+2xy+y^2=49
所以x^2+y^2=25
(x-y)^2=(x^2+y^2)-2xy=1
所以x-y=1或-1
猜你喜欢
- 1I‘m going to buy a big house next year 对 next year 提问
- 2在不计空气阻力的情况下,质量为m的物体从距地面H高处由静止开始下落,...
- 3仿写句子:兴安岭多么会打扮自己呀:青松作衫,白桦为裙,还穿着绣花鞋.
- 4They speak ( ) ( America) English
- 5i don‘t know what to say...i‘m just thinking of you a lot at this moment.翻译中文是?
- 61条直线将平面分为2部分,2条分4不分,3条分7部分,4条分11部分,N条分S部分,写出S关于N的表达式
- 7不变的是友谊 作文
- 8在比例词是1:250000的地图上,量的甲乙两地的距离是60厘米,如果把甲乙两地的距离画在比例尺是1:500000的
- 9what do your parents look like?please describe them in few sentences My mother is_____________,she
- 10suddenly he heard the door opened翻译成英语