已知(a+b)²=9,(a-b)²=4,求a²+b²和ab的值谢谢!O(∩_∩)O谢谢!
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/02 04:11:31
![已知(a+b)²=9,(a-b)²=4,求a²+b²和ab的值谢谢!O(∩_∩)O谢谢!](/uploads/image/z/14911175-47-5.jpg?t=%E5%B7%B2%E7%9F%A5%28a%2Bb%29%26%23178%3B%3D9%2C%28a-b%29%26%23178%3B%3D4%2C%E6%B1%82a%26%23178%3B%2Bb%26%23178%3B%E5%92%8Cab%E7%9A%84%E5%80%BC%E8%B0%A2%E8%B0%A2%21O%28%E2%88%A9_%E2%88%A9%29O%E8%B0%A2%E8%B0%A2%21)
已知(a+b)²=9,(a-b)²=4,求a²+b²和ab的值谢谢!O(∩_∩)O谢谢!
已知(a+b)²=9,(a-b)²=4,求a²+b²和ab的值
谢谢!O(∩_∩)O谢谢!
已知(a+b)²=9,(a-b)²=4,求a²+b²和ab的值谢谢!O(∩_∩)O谢谢!
(a+b)²=a²+2ab+b²=9
(a-b)²=a²-2ab+b²=4
两式相加得
2a²+2b²=13
a²+b²=13/2
两式相减得
4ab=5
ab=5/4