Question

已知y=y1-y2.y1与x成反比例,y2与(x-2)成正比例,并且当x=3时,y=5；当x=1时,y=-1,求y与x之

Answer 1

y1=k/x

y2=m(x-2)

y=k/x-m(x-2)

x=3

y=k/3-m=5 (1)

x=1

y=k+m=-1 (2)

(1)+(2)

4k/3=4

k=3

m=-4

所以y=3/x+4x-8