Question

已知,二次函数y=-0.5x²-（m+3)x+m²-12的图像与x轴相交于A(x1,0),B(x2,

Answer 1

(1)-0.5x²-（m+3)x+m²-12=0

x²+2（m+3)x+(24-2m²)=0

△=4(m+3)²-4(24-2m²)

=12m²+24m-60

=4(3m²+6m-15)

X1=-(m+3)-√(3m²+6m-15),X2=-(m+3)+√(3m²+6m-15)

OB=2OA,-2X1=X2

2(m+3)+2√(3m²+6m-15)=-(m+3)+√(3m²+6m-15)

3(m+3)=-√(3m²+6m-15)

m+3