题目

Two friends have an argument that breaks up their friendship forever, even though neither one can remember how the whole thing got started. Such sad events happen over and over in high schools across the country. In fact, according to an official report on youth violence, “In our country today, the greatest threat to the lives of children and adolescents is not disease or starvation or abandonment, but the terrible reality of violence”. Given that this is the case, why aren’t students taught to manage conflict the way they are taught to solve math problems, drive cars, or stay ph已知如图：二次函数y=ax2+bx+c的图象与x轴交于A、B两点，与y轴交于点C，若AC=20，BC=15，∠ACB=90O,求：二次函数解析式。