w>0,x∈ [-π/3,π/4],
则wx∈ [-wπ/3,wπ/4].
区间[-wπ/3,wπ/4]包含原点,而原点附近函数取到最小值-2,
则需区间包含-π/2
所以-wπ/3≤-π/2,w≥3/2.
w的最小值是3/2.