Question

已知y=y1+y2,y1与x成正比例,y2与x成反比例,且x=1与x=2时,y的值都等于6 （1）求y与x的函数关系式,

Answer 1

设y1=ax

y2=b/x

当x=1时,y1=a,y2=b,y1+y2=a+b=6;a=6-b

当x=2时,y1=2a,y2=b/2,y1+y2=2a+b/2=6

12-2b+b/2=6,b=4,a=2

即,

y=2x+4/x