求这三个二次元函数的对称轴和顶点坐标Y=-5X²+80X-319Y=2(X-1/2)(X-2)Y=2X²-12X+13

Question

求这三个二次元函数的对称轴和顶点坐标
Y=-5X²+80X-319
Y=2(X-1/2)(X-2)
Y=2X²-12X+13

Answer 1

Y=-5X²+80X-319=-5（x²-16x）-319=-5(x²-16x+64-64)-319=-5[(x-8)²-64]-319=-5(x-8)²+320-319=-5(x-8)²+1∴对称轴是直线X＝8,顶点坐标是（8,1）.Y=2(X-1/2)(X-2)＝2[x²-(5/2)x+1...