Question

二次函数

已知抛物线y=x²+bx+c与y轴交与点A，与x轴的正半轴交与B，C两点，且BC=2，S△ABC=3，则b=_____,c=_____
说明理由

Answer 1

A(0,c), B=([-b+√(b^2-4c)]/2, 0 ),
C=([-b-√(b^2-4c)]/2, 0 )

BC = 2
b^2-4c = 4

and
area = 1/2BC .c
= 1/2(2) c = 3
=> c = 3
=> c = 3

b^2-4c = 4
b^2 = 16
b = -4 or 4 (rejected)