5000 * (1 + x) ^2 = 7200

问题描述:

5000 * (1 + x) ^2 = 7200

5000 * (1 + x) ^2 = 7200
(1 + x) ² = 7200 /5000=1.44
1 + x = √1.44=1.2
x=0.2=20%