若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²+2y²²的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/23 18:41:05
![若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²+2y²²的值](/uploads/image/z/1002412-28-2.jpg?t=%E8%8B%A5x%26%23178%3B%EF%BC%8By%26%23178%3B%3D7%2Cxy%3D-2%2C%E6%B1%825x%26%23178%3B-3xy-4y%26%23178%3B-11xy-7x%26%23178%3B%2B2y%26%23178%3B%26%23178%3B%E7%9A%84%E5%80%BC)
若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²+2y²²的值
若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²+2y²²的值
若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²+2y²²的值
x²+y²=7 转成 x²=7-y²
将 xy=-2 和 x²=7-y² 代人(5x²-3xy-4y²-11xy-7x²+2y²)² 中得出
[5(7-y² )-3(-2)-4y²-11(-2)-7(7-y²)+2y² ]²
整理后得 (41-9y²-27+9y²)² =14² =196