Question

如图,已知抛物线y=ax^2+bx+c经过a(0,2)b(4,0)c（5,-3）三点,求抛物线的解析式,

Answer 1

将a(0,2)b(4,0)c（5,-3）三点的坐标代入y=ax^2+bx+c,得

{c=2

16a+4b+c=0

25a+5b+c=-3

解得：{a= - ½

b= 3/2

c=2

∴抛物线的解析式是：y=-½x²+(3/2)x+2