950=60/(1+r)+50/(1+r)^2,

Question

950=60/(1+r)+50/(1+r)^2,

Answer 1

令a=1/(1+r)
则950=60a+50a²
5a²+6a-95=0
(5a-19)(a+5)=0
a=19/5,a=-5
1/(1+r)=19/5
1+r=5/19
r=-14/19
1/(1+r)=-5
1+r=-1/5
r=-9/5
所以r=-14/19,r=-6/5