先化简,在求值.[(m-3)/(3m²-6m)]/[m+2-5/(m-2)] ,其中m是方程x²+3x-1=0的根
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/24 00:13:54
![先化简,在求值.[(m-3)/(3m²-6m)]/[m+2-5/(m-2)] ,其中m是方程x²+3x-1=0的根](/uploads/image/z/594322-34-2.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%9C%A8%E6%B1%82%E5%80%BC.%5B%EF%BC%88m-3%EF%BC%89%2F%283m%26%23178%3B-6m%29%5D%2F%5Bm%2B2-5%2F%28m-2%29%5D+%2C%E5%85%B6%E4%B8%ADm%E6%98%AF%E6%96%B9%E7%A8%8Bx%26%23178%3B%2B3x-1%3D0%E7%9A%84%E6%A0%B9)
先化简,在求值.[(m-3)/(3m²-6m)]/[m+2-5/(m-2)] ,其中m是方程x²+3x-1=0的根
先化简,在求值.[(m-3)/(3m²-6m)]/[m+2-5/(m-2)] ,其中m是方程x²+3x-1=0的根
先化简,在求值.[(m-3)/(3m²-6m)]/[m+2-5/(m-2)] ,其中m是方程x²+3x-1=0的根
原式=(m-3)/[3m(m-2)]·[﹙m+2﹚﹙m+2﹚-5]/﹙m-2﹚
=(m-3)/[3m(m-2)]·(m-2)/[﹙m+2﹚﹙m+2﹚-5]
=(m-3)/3m[﹙m²-4﹚-5]
=﹙m-3﹚/3m³-27m
=﹙m-3﹚/3m(m²-9)
=﹙m-3﹚/3m﹙m+3﹚﹙m-3﹚
=1/3m²+9m
因为m是方程x²+3x-1=0,则m²+3m-1=0即m²=1-3m带入原式得1/3-9m+9m=1/3