Question

已知Y等于Y1-Y2,Y1与x+2成反比例,Y2与x²成正比例.当x=1时,Y＝-1,当x等于-3时,y=-2

Answer 1

y1=a/(x+2)

y2=bx²

y=a/(x+2)-bx²

-1=a/3-b

-21=-a-9b

解得 a=3 b=2

y=3/(x+2)-2x²

当x=2 y=3/4-8=-29/4