初中到高中的数学问题及答案
假设:f(x)=x?+2(m-1)x+2m+6
1,正好:f (2) < 0,你得到:4+4 (m-1)+2m+6
2、仿照上面的例子,结合图像,有:
f(0)>0 = = = & gt& gt& gt2m+6 & gt;0 = = = = & gt& gt& gtm & gt-3
f(1)& lt;0 = = >;& gt& gt& gt1+2(m-1)+2m+6 & lt;0 = = = & gt& gt& gt& gtm & lt-5/4
f(4)>0 = = = & gt& gt& gt16+8(m-1)+2m+6 & gt;0 = = = & gt& gt& gtm & gt-7/5
综合起来,M的范围是:-7/5