方程①X²-2MX+M²-M=0②X²-(4M+1)X+4M²+M=0③4X²-(12M+4)X+9M²+8M+12=0求M的取值范围
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/23 23:41:59
![方程①X²-2MX+M²-M=0②X²-(4M+1)X+4M²+M=0③4X²-(12M+4)X+9M²+8M+12=0求M的取值范围](/uploads/image/z/3162457-1-7.jpg?t=%E6%96%B9%E7%A8%8B%E2%91%A0X%26%23178%3B-2MX%2BM%26%23178%3B-M%3D0%E2%91%A1X%26%23178%3B-%EF%BC%884M%2B1%EF%BC%89X%2B4M%26%23178%3B%2BM%3D0%E2%91%A24X%26%23178%3B-%EF%BC%8812M%2B4%EF%BC%89X%2B9M%26%23178%3B%2B8M%2B12%3D0%E6%B1%82M%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4)
方程①X²-2MX+M²-M=0②X²-(4M+1)X+4M²+M=0③4X²-(12M+4)X+9M²+8M+12=0求M的取值范围
方程①X²-2MX+M²-M=0②X²-(4M+1)X+4M²+M=0③4X²-(12M+4)X+9M²+8M+12=0
求M的取值范围
方程①X²-2MX+M²-M=0②X²-(4M+1)X+4M²+M=0③4X²-(12M+4)X+9M²+8M+12=0求M的取值范围
方程的判别式⊿≥0,方程才有实数根
① x²-2mx+m²-m=0
⊿=(-2m)²-4×1×(m²-m)
=4m²-4m²+4m
=4m
所以4m≥0,m≥0
② x²-(4m+1)x+4m²+m=0
⊿=[-(4m+1)]²-4×1×(4m²+m)
=16m²+8m+1-16m²-4m
=4m+1
所以4m+1≥0,m≥-1/4
③ 4x²-(12m+4)x+9m²+8m+12=0
⊿=[-(12m+4)]²-4×4×(9m²+8m+12)
=144m²+96m+16-144m²-128m-192
=-32m-176
所以-32m-176≥0,m≤ -11/2
LZ强淫 2L也是