函数y=-sin^2x+sinx+4/7的最小值

问题描述:

函数y=-sin^2x+sinx+4/7的最小值

y=-sin^2x+sinx+4/7
=-(sinx)^2+sinx+4/7
=-(sinx-1/2)^2+1/4+4/7
=-(sinx-1/2)^2+23/28
-1不好意思,是函数y=-sin^2x+sinx+7/4的最小值一样的做法。y=-sin^2x+sinx+7/4=-(sinx)^2+sinx+7/4=-(sinx-1/2)^2+1/4+7/4=-(sinx-1/2)^2+2-1