10% (b) Show that if f(x)<0, then f(x) is concave downward.

I. Translate the following into Chinese. After a late-night thrilling to the view of the Milky Way along the dark shores of Lake Superior, I climbed into bed prepared for a long sleep and a morning reveling in the experience. That didn't happen. Instead, I awoke at daybreak to a saturated sky alight with color. Stepping outside my rental cabin a few feet from the lake, I was immersed in the colors: blazing orange, searing yellow and a brilliant white line at the horizon. The water glistened as the sun began to emerge, calm waters quietly tapping the shore where aspen and birch leaves rippled in the crisp September morning. It nearly took my breath away. This panoramic sunrise was like none I had ever seen, and it moved me in ways that are hard to explain. I had come to Michigan's wild and wondrous Upper Peninsula hoping to find transformative experiences that would soothe a pandemic-weary soul. I wanted to mark these strange times with something stunning, instead of only crisis and tragedy. So I headed north and let the stars guide my way. The skies were clear and it was a little before midnight when my friends and I drove to Whitefish Point to look for the Milky Way. We climbed the wooden deck on the Lake Superior shore, near where the SS Edmund Fitzgerald sank in 1975. (Excerpted from Chicago Tribune) (詞彙表: Lake Superior 蘇必略湖 Michigan 密歇根州 Upper Peninsula 上半岛 Whitefish Point 懷特菲什角 SSEdmund Fitzgerald 埃德蒙德·费茲羅號)

題組內容

10% (b) Show that if f(x)<0, then f(x) is concave downward.

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