求函数y=(4-cosx)/(2cosx+3)的最值
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求函数y=(4-cosx)/(2cosx+3)的最值
求函数y=(4-cosx)/(2cosx+3)的最值
求函数y=(4-cosx)/(2cosx+3)的最值
1/y=(2cosx+3)/(4-cosx)=-2+11/(4-cosx)
-1≤cosx≤1
-1≤-cosx≤1
3≤4-cosx≤5
11/5≤11/(4-cosx)≤11/3
1/5≤-2+11/(4-cosx)≤5/3
3/5≤y≤5
所以最大值=5,最小值=3/5
1/y=(2cosx+3)/(4-cosx)=-2+11/(4-cosx)
-1≤cosx≤1
-1≤-cosx≤1
3≤4-cosx≤5
11/5≤11/(4-cosx)≤11/3
1/5≤-2+11/(4-cosx)≤5/3
3/5≤y≤5