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

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